Curable composition for imprints, patterning method and pattern

ABSTRACT

Provided is a curable composition for imprints having good patternability and dry etching resistance. Disclosed is a curable composition for imprints comprising a polymerizable monomer (Ax) having a substituent having an aromatic group and having a molecular weight of 100 or more, and a photopolymerization initiator.

TECHNICAL FILED

The present invention relates to a curable composition for imprints, apatterning method and a pattern.

BACKGROUND ART

Imprint technology is a development advanced from embossing technologywell known in the art of optical disc production, which comprisespressing a mold original with an embossed pattern formed on its surface(this is generally referred to as “mold”, “stamper” or “template”)against a resin to thereby accurately transfer the micropattern onto theresin through mechanical deformation of the resin. In this, when a moldis once prepared, then microstructures such as nanostructures can berepeatedly molded, and therefore, this is economical, and in addition,harmful wastes and discharges from this nanotechnology are reduced.Accordingly these days, this is expected to be applicable to varioustechnical fields.

Two methods of imprint technology have been proposed; one is a thermalimprint method using a thermoplastic resin as the material to be worked(for example, see S. Chou, et al., Appl. Phys. Lett. Vol. 67, 3114(1995)), and the other is a photoimprint method using a photocurablecomposition (for example, see M. Colbun, et al., Proc. SPIE, Vol. 3676,379 (1999)). In the thermal imprint method, a mold is pressed against apolymer resin heated up to a temperature not lower than the glasstransition temperature thereof, then the resin is cooled and thereafterreleased from the mold to thereby transfer the microstructure of themold onto the resin on a substrate. The method is applicable to variousresin materials and glass materials and is expected to be applicable tovarious fields. For example, U.S. Pat. Nos. 5,772,905 and 5,956,216disclose a imprint method of forming nanopatterns inexpensively.

On the other hand, in the photoimprint method where a composition forphotoimprints is photocured by photoirradiation through a transparentmold or a transparent substrate, the transferring material does notrequire heating in pressing it against the mold, and therefore themethod enables room-temperature imprinting. Recently, new developmentshaving the advantages of the above two as combined, have been reported,including a nanocasting method and a reversal imprint method for formingthree-dimensional structures.

For the imprint methods as above, proposed are applied technologies tonano-scale mentioned below.

In the first technology, the molded pattern itself has a function, andis applied to various elements in nanotechnology and to structuralmembers. Its examples include various micro/nano optical elements andhigh-density recording media, as well as structural members in opticalfilms, flat panel displays, etc. The second technology is forhybrid-molding of microstructures and nanostructures, or forconstruction of laminate structures through simple interlayerpositioning, and this is applied to production of μ-TAS (micro-totalanalysis system) and biochips. In the third technology, the formedpattern is used as a mask and is applied to a method of processing asubstrate through etching or the like. In these technologies,high-precision positioning is combined with high-density integration;and in place of conventional lithography technology, these technologiesare being applied to production of high-density semiconductor integratedcircuits and transistors in liquid-crystal displays, and also tomagnetic processing for next-generation hard discs referred to aspatterned media. Recently, the action on industrialization of theabove-mentioned imprint technologies and their applied technologies hasbecome active for practical use thereof.

As one example of imprint technology, hereinunder described is anapplication to production of high-density semiconductor integratedcircuits. The recent development in micropatterning and integrationscale enlargement in semiconductor integrated circuits is remarkable,and high-definition photolithography for pattern transfer for realizingthe intended micropatterning is being much promoted and advanced in theart. However, for further requirement for more definite micropatterningto a higher level, it is now difficult to satisfy all the three ofmicropattern resolution, cost reduction and throughput increase.Regarding this, as a technology of micropatterning capable of attainingat a low cost, imprint lithography, particularly nanoimprint lithography(photonanoimprint technology) is proposed. For example, U.S. Pat. Nos.5,772,905 and 5,259,926 disclose a nanoimprint technology of using asilicon wafer as a stamper for transferring a microstructure of at most25 nm. This application requires micropatternability on a level of a fewtens nm and high-level etching resistance of the micropatternfunctioning as a mask in substrate processing.

An application example of imprint technology to production ofnext-generation hard disc drives (HDD) is described. Based on headperformance improvement and media performance improvement closelyconnected with each other, the course of HDD history is for capacityincrease and size reduction. From the viewpoint of media performanceimprovement, HDD has realized increased large-scale capacity as a resultof the increase in the surface-recording density thereon. However, inincreasing the recording density, there occurs a problem of so-calledmagnetic field expansion from the side surface of the magnetic head. Themagnetic field expansion could not be reduced more than a certain leveleven though the size of the head is reduced, therefore causing aphenomenon of so-called sidelight. The sidelight, if any, causeserroneous writing on the adjacent tracks and may erase the alreadyrecorded data. In addition, owing to the magnetic field expansion, theremay occur another problem in that superfluous signals may be read fromthe adjacent track in reproduction. To solve these problems, there areproposed technologies of discrete track media and bit patterned media offilling the distance between the adjacent tracks with a non-magneticmaterial to thereby physically and magnetically separate the tracks. Asa method of forming the magnetic or non-magnetic pattern in productionof these media, application of imprint technology is proposed. Theapplication also requires micropatternability on a level of a few tensnm and high-level etching resistance of the micropattern functioning asa mask in substrate processing.

Next described is an application example of imprint technology to flatdisplays such as liquid-crystal displays (LCD) and plasma display panels(PDP).

With the recent tendency toward large-sized LCD substrates and PDPsubstrates for high-definition microprocessing thereon, photoimprintlithography has become specifically noted these days as an inexpensivelithography technology capable of being substituted for conventionalphotolithography for use in production of thin-film transistors (TFT)and electrode plates. Accordingly, it has become necessary to develop aphotocurable resist capable of being substituted for the etchingphotoresist for use in conventional photolithography.

Further, for the structural members for LCD and others, application ofphotoimprint technology to transparent protective film materialsdescribed in JP-A-2005-197699 and 2005-301289, or to spacers describedin JP-A-2005-301289 is being under investigation. Differing from theabove-mentioned etching resist, the resist for such structural membersfinally remains in displays, and therefore, it may be referred to as“permanent resist” or “permanent film”.

The spacer to define the cell gap in liquid-crystal displays is also atype of the permanent film; and in conventional photolithography, aphotocurable composition comprising a resin, a photopolymerizablemonomer and an initiator has been generally widely used for it (forexample, see JP-A-2004-240241). In general, the spacer is formed asfollows: After a color filter is formed on a color filter substrate, orafter a protective film for the color filter is formed, a photocurablecomposition is applied thereto, and a pattern having a size of from 10μm or 20 μm or so is formed through photolithography, and this isfurther thermally cured through past-baking to form the intended spacer.

Further, imprint lithography is useful also in formation of permanentfilms in optical members such as microelectromechanical systems (MEMS),sensor devices, gratings, relief holograms, etc.; optical films forproduction of nanodevices, optical devices, flat panel displays, etc.;polarizing elements, thin-film transistors in liquid-crystal displays,organic transistors, color filters, overcoat layers, pillar materials,rib materials for liquid-crystal alignment, microlens arrays,immunoassay chips, DNA separation chips, microreactors, nanobio devices,optical waveguides, optical filters, photonic liquid crystals, etc.

In application to such permanent films, the formed pattern remains inthe final products, and is therefore required to have high-levelproperties of mainly film durability and strength, including heatresistance, light resistance, solvent resistance, scratch resistance,high-level mechanical resistance to external pressure, hardness, etc.

Almost all patterns heretofore formed in conventional photolithographycan be formed in imprint technology, which is therefore specificallynoted as a technology capable of forming micropatterns inexpensively.

In the case where nanoimprint is industrially utilized, variousproperties depending on an intended use such as described above arerequired in addition to good patternability. For example, in applicationfor a fabricated substrate, high-level etching resistance is required.

JP-A-2006-310565 and JP-A-2007-186570 suggest a composition comprising acyclic monomer or a composition satisfying a particular parameter forthe purpose of improving dry etching resistance. However, thosecompositions are not sufficient from the viewpoints of achievement ofpatternability and dry etching resistance.

SUMMARY

As described above, a composition satisfying high-level patternabilityand high-level dry etching resistance has been studied. However, acomposition excellent in both of patternability and dry etchingresistance has not been provided. It is an object of the presentinvention to solve the above problem, and to provide a curablecomposition for imprints which is excellent in patternability and dryetching resistance.

Given the situation as above, the present inventors have assiduouslystudied and has found that a curable composition for imprints which isexcellent in patternability and dry etching resistance tends to beobtained by using a (meth)acrylate having an aromatic group andsatisfying a particular requirement. In particular, while a curablecomposition excellent in patternability and dry etching resistance isnot obtained by using benzylacrylate, which is a representative acrylatehaving an aromatic group, a composition excellent in both ofpatternability and dry etching resistance is obtained by using the(meth)acrylate defined in the present invention. Therefore, thecomposition of the present invention is extremely innovative.

Specifically, the present problem has solved by the following means;

[1] A curable composition for imprints comprising a polymerizablemonomer (Ax) and a photopolymerization initiator, wherein thepolymerizable monomer (Ax) is represented by the following formula (I);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; Z is a group having an aromatic group and having a molecularweight of 100 or more; and, when the polymerizable monomer (Ax) isliquid at 25° C., the polymerizable monomer (Ax) has a viscosity of 500mPa·s or less.

[2] The curable composition for imprints according to [1], wherein Z inthe formula (I) represents —Z¹—Z²; wherein Z¹ is a single bond, or ahydrocarbon group which may have a linking group containing a heteroatom in the chain of the linking group; Z² is an aromatic group having amolecular weight of 90 or more; and Z² may have a substituent.

[3] The curable composition for imprints according to [1], wherein thepolymerizable monomer (Ax) is a compound represented by the followingformula (II);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X¹ is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y¹ represents a substituent having a molecular weight of 15 ormore; n1 represents an integer of 0 to 3; when n1 is 0, X¹ is ahydrocarbon group having two or more carbon atoms; and Ar is a phenylenegroup, or an aromatic group having two or more aromatic rings bonded toeach other in series.

[4] The curable composition for imprints according to [1], wherein thepolymerizable monomer (Ax) is a compound represented by the followingformula (III);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X¹ is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y¹ represents a substituent having a molecular weight of 15 ormore; n1 represents an integer of 0 to 3; and, when n1 is 0, X¹ is ahydrocarbon group having two or more carbon atoms.

[4-2] The curable composition for imprints according to [4], wherein X¹is an alkylene group.

[4-3] The curable composition for imprints according to [4], wherein X¹is —CH₂—.

[5] The curable composition for imprints according to [1], wherein thepolymerizable monomer (Ax) is a compound represented by the followingformula (IV);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X² is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y² represents a substituent having a molecular weight of 15 ormore, the substituent being other than an aromatic group-containinggroup; n2 represents an integer of 0 to 3; and, when n2 is 0, X² is ahydrocarbon group having two or three carbon atoms.

[5-2] The curable composition for imprints according to [5], wherein X²in the formula (IV) is an alkylene group.

[5-3] The curable composition for imprints according to [5], wherein X²in the formula (IV) is —CH₂—.

[6] The curable composition for imprints according to [5], wherein, inthe formula (IV), R¹ is a hydrogen atom, or a methyl group; X² is asingle bond, or a hydrocarbon group having 1 to 3 carbon atoms; n² is aninteger of 0 to 2; and, when n2 is 2, X² is a hydrocarbon group havingone carbon atom.

[7] The curable composition for imprints according to [5] or [6],wherein the compound represented by the formula (IV) has a molecularweight of 175 to 250.

[8] The curable composition for imprints according to any one of [5] to[7], wherein the compound represented by the formula (IV) has aviscosity of 6 mPa·s or less at 25° C.

[9] The curable composition for imprints according to [1], wherein thepolymerizable monomer (Ax) is a compound represented by the followingformula (V);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X³ is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y³ represents a substituent having an aromatic group and having amolecular weight of 15 or more; and n3 represents an integer of 1 to 3.

[9-2] The curable composition for imprints according to [9], wherein X³in the formula (V) is an alkylene group.

[9-3] The curable composition for imprints according to [9], wherein X³in the formula (V) is —CH₂—.

[10] The curable composition for imprints according to [9], wherein R¹is a hydrogen atom, or an alkyl group, and X³ is a single bond, or analkylene group.

[11] The curable composition for imprints according to [1], wherein thepolymerizable monomer (Ax) is a compound represented by the followingformula (VI);

wherein X⁶ is a (n6+1)-valent linking group; R¹ each are a hydrogenatom, an alkyl group, or a halogen atom; R² and R³ each are asubstituent; n4 and n5 each are an integer of 0 to 4; n6 is 1 or 2; andX⁴ and X⁵ each are a hydrocarbon group which may have a linking groupcontaining a hetero atom in the chain of the linking group.

[11-2] The curable composition for imprints according to [11], whereinX⁴ and X⁵ in the formula (V) each are an alkylene group.

[11-3] The curable composition for imprints according to [11], whereinX⁴ and X⁵ in the formula (V) each are —CH₂—.

[12] The curable composition for imprints according to [11], wherein X⁴and X⁵ in the formula (VI) each are an alkylene group, the alkylenegroup being free from a linking group.

[13] The curable composition for imprints according to any one of [1] to[12], which further comprises a polymerizable monomer different from thepolymerizable monomer (Ax).

[14] The curable composition for imprints according to [13], wherein thepolymerizable monomer different from the polymerizable monomer (Ax) is amonofunctional (meth)acrylate having an aromatic structure and/or analicyclic hydrocarbon structure.

[15] The curable composition for imprints according to any one of [1] to[14], which further comprises a polymerizable compound having a fluorineatom and/or a silicon atom.

[16] The curable composition for imprints according to any one of [1] to[15], which further comprises an antioxidant and/or a surfactant.

[17] The curable composition for imprints according to any one of [1] to[16], which comprises 30% by mass or less of polymerizable monomershaving a molecular weight of 2000 or more, relative to the total amountof all the polymerizable monomers contained in the composition.

[18] A cured product of the curable composition for imprints accordingto any one of [1] to [17].

[19] A method for manufacturing a cured product comprising;

applying the curable composition for imprints according to any one of[1] to [17] onto a substrate to form a patterning layer thereon,

pressing a mold against the surface of the patterning layer, and

irradiating the patterning layer with light.

[20] A reaction diluent comprising a compound represented by thefollowing formula (IV);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X² is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y² represents a substituent having a molecular weight of 15 ormore, the substituent being other than an aromatic group-containinggroup; n2 represents an integer of 0 to 3; and, when n2 is 0, X² is ahydrocarbon group having two or three carbon atoms.

[21] The curable composition for imprints according to any one of [1] to[17], wherein the polymerizable monomer (Ax) has a benzyl(meth)acrylateskeleton.

[22] The curable composition for imprints according to any one of [1] to[17], wherein the polymerizable monomer (Ax) is a partial derivative ofbenzyl(meth)acrylate.

[23] The curable composition for imprints according to [13] or [14],wherein the polymerizable monomer (Ax) is a polyfunctional(meth)acrylate having a benzyl(meth)acrylate skeleton.

The composition of the present invention can provide a cured articlewhich exhibits a good patternability and has an excellent dry etchingresistance.

DETAILED DESCRIPTION OF INVENTION

The contents of the present invention are described in detailhereinunder. In this specification, the numerical range expressed by thewording “a number to another number” means the range that falls betweenthe former number indicating the lowermost limit of the range and thelatter number indicating the uppermost limit thereof. In thisspecification, mass ratio is equal to weight ratio.

In this specification, “(meth)acrylate” means acrylate and methacrylate;“(meth)acrylic” means acrylic and methacrylic; “(meth)acryloyl” meansacryloyl and methacryloyl. In the present invention, monomer isdifferentiated from oligomer and polymer, and the monomer indicates acompound having a weight-average molecular weight of at most 1,000. Inthis specification, “functional group” means a group participating inpolymerization. “Imprint” referred to in the present invention is meantto indicate pattern transfer in a′ size of from 1 nm to 10 mm andpreferably meant to indicate pattern transfer in a size of from about 10nm to 100 μm (nanoimprint).

Regarding the expression of “group (atomic group)” in thisspecification, the expression with no indication of “substituted” or“unsubstituted” includes both “substituted group” and “unsubstitutedgroup”. For example, “alkyl group” includes not only an alkyl group nothaving a substituent (unsubstituted alkyl group) but also an alkyl grouphaving a substituent (substituted alkyl group).

[Curable Composition for Imprints in the Present Invention]

The curable composition for imprints in the present invention (which maybe hereinafter simply referred to as the “composition of the presentinvention”) is a curable composition for imprints comprising one or morepolymerizable monomers and a photopolymerization initiator, wherein atleast one of the polymerizable monomers is a polymerizable monomer (Ax)represented by the following formula (I);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; Z is a group having an aromatic group and having a molecularweight of 100 or more; and, when the polymerizable monomer (Ax) isliquid at 25° C., the polymerizable monomer (Ax) has a viscosity of 500mPa·s or less.

R¹ is preferably a hydrogen atom, or an alkyl group, more preferably ahydrogen atom, or a methyl group, further more preferably a hydrogenatom from the viewpoint of the curability of the composition. Examplesof the halogen atom include fluorine atom, chlorine atom, bromine atom,and iodine atom, and preferred is fluorine atom.

Z is an aralkyl group which may have a substituent, an aryl group whichmay have a substituent, or a group in which those groups are bonded toeach other via a linking group. The linking group may include a heteroatom. The linking group is preferably —CH₂—, —O—, —C(═O)—, —S—, or acombination thereof. The aromatic group contained in Z is preferably aphenyl group. More preferably, z contains only a phenyl group as thearomatic group. Compared with a group containing a polyaromatic group,or a heteroaromatic group, the group having only a phenyl group as thearomatic group contained in Z attains low viscosity and goodpatternability, and reduces particle failure. The molecular weight of Zis preferably 100 to 300, more preferably 120 to 250.

The number of the polymerizable groups in the polymerizable monomer (Ax)is preferably not more than the number of the aromatic groups in view ofthe viscosity of the composition and dry etching resistance (the numberof polymerizable groups≦the number of aromatic groups). In the case of acondensed ring such as naphthalene, it is counted as one aromatic group.In the case where two or more aromatic rings are bonded via a singlebond or a linking group such as a biphenyl group, it is counted as twoor more aromatic groups.

When the polymerizable monomer (Ax) is liquid at 25° C., the viscositythereof is preferably 2 to 500 mPa·s at 25° C., more preferably 3 to 200mPa·s, further more preferably 3 to 100 mPa·s. The polymerizable monmer(Ax) is preferably liquid at 25° C., or solid having a melting point of60° C. or less, more preferably liquid at 25° C., or solid having amelting point of 25° C. or less.

Z preferably represents —Z¹—Z². Z¹ is a single bond, or a hydrocarbongroup which may have a linking group containing a hetero atom in thechain thereof. Z² is an aromatic group which may have a substituent. Z²has a molecular weight of 90 or more.

Z¹ is preferably a single bond, or an alkylene group which may have alinking group containing a hetero atom in the chain of the linkinggroup. Z¹ is more preferably an alkylene group not having a linkinggroup containing a hetero atom in the chain thereof, more preferably amethylene group, or an ethylene group. Examples of the linking groupcontaining a hetero atom include —O—, —C(═O)—, —S—, and a combination ofan alkylene group and at least one of —O—, —C(═O)— and —S—. The numberof the carbon atoms of Z¹ is preferably 1 to 3.

Z² is preferably an aromatic group having a substituent having amolecular weight of 15 or more. Examples of the aromatic group in Z²include a phenyl group and a naphthyl group. Z² is more preferably aphenyl group having a substituent having a molecular weight of 15 ormore. Z² preferably comprises a monocyclic aromatic group.

Z² is also preferably a group in which two or more aromatic groupsdirectly bond to each other, or a group in which two or more aromaticgroups bond to each other via a linking group. The linking group ispreferably —CH₂—, —O—, —C(═O)—, —S—, or a combination thereof.

Examples of a substituent which the aromatic group may have include ahalogen atom (fluorine atom, chlorine atom, bromo atom, iodine atom), alinear, a branched, or a cyclic alkyl group, an alkenyl group, analkynyl group, an aryl group, an acyl group, an alkoxycarbonyl group, anaryloxycarbonyl group, a carbamoyl group, a cyano group, a carboxylgroup, a hydroxy group, an alkoxy group, an aryloxy group, an alkylthiogroup, an arylthio group, a heterocyclic-oxy group, an acyloxy group, anamino group, a nitro group, a hydrazino group, a heterocyclic group. Agroup which is substituted with those groups is also preferred.

The polymerizable monomer (Ax) is preferably liquid at 25° C. When thepolymerizable monomer (Ax) is liquid, the viscosity at 25° C. is 500mPa·s or less, preferably 300 mPa·s or less, more preferably 200 mPa·sor less, further more preferably 100 mPa·s or less.

The amount of the compound represented by the formula (I) to be added inthe composition is preferably 10 to 100% by mass, more preferably 20 to100% by mass, furthermore preferably 30 to 80% by mass.

The compound represented by the formula (I) is preferably represented bythe following formula (II);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X¹ is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y¹ represents a substituent having a molecular weight of 15 ormore; n1 represents an integer of 0 to 3; when n1 is 0, X¹ is ahydrocarbon group having two or more carbon atoms; and Ar is a phenylenegroup, or an aromatic group having two or more aromatic rings bonded toeach other in series.

Ar is preferably a phenylene group.

R¹ is the same as R¹ in the above formula (I) and the preferable rangethereof is the same as R¹ in the above formula (I).

X¹ is the same as Z¹ in the above and the preferable range thereof isthe same as Z¹ in the above. Y¹ is a substituent having a molecularweight of 15 or more. Examples of Y¹ include an alkyl group, an alkoxygroup, an aryloxy group, an alkenyl group, an aralkyl group, an acylgroup, an alkoxycarbonyl group, an alkylthio group, an arylthio group,and a halogen atom. Those substituents may have a substituent.

When n1 is 0, X¹ is preferably an alkylene group having 2 or 3 carbonatoms. When n1 is 2, X¹ is preferably a hydrocarbon group having 1carbon atom.

In particular, the more preferred embodiment is that n1 is 1 and X¹ isan alkylene group having 1 to 3 carbon atoms.

The compound represented by the formula (II) is more preferablyrepresented by the following formula (III);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X¹ is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y¹ represents a substituent having a molecular weight of 15 ormore; n1 represents an integer of 0 to 3; and, when n1 is 0, X¹ is ahydrocarbon group having two or more carbon atoms.

R¹ is the same as R¹ in the above formula (I) and the preferable rangethereof is the same as R¹ in the above formula (I).

X¹ is the same as Z¹ in the above and the preferable range thereof isthe same as Z¹ in the above.

Y¹ is the same as Y¹ in the above formula (II) and the preferable rangethereof is the same as Y¹ in the above formula (II).

n1 is the same as n1 in the above formula (II) and the preferable rangethereof is the same as n1 in the above formula (II).

The compound represented by the formula (III) is further preferably acompound represented by any one of the formulae (IV) to (VI).

The compound represented by the formula (IV);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X² is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y² represents a substituent having a molecular weight of 15 ormore, the substituent being other than an aromatic group-containinggroup; n2 represents an integer of 0 to 3; and, when n2 is 0, X² is ahydrocarbon group having two or three carbon atoms.

R¹ is the same as R¹ in the above formula (I) and the preferable rangethereof is the same as R¹ in the above formula (I).

When X² is a hydrocarbon group, X² is preferably a hydrocarbon grouphaving 1 to 3 carbon atoms, more preferably a substituted orunsubstituted alkylene group having 1 to 3 carbon atoms, furthermorepreferably an unsubstituted alkylene group having 1 to 3 carbon atoms,still more preferably an ethylene group. By applying such a hydrocarbongroup, it makes possible to provide a composition having lower viscosityand lower volatility.

Y² represents a substituent which has a molecular weight of 15 or moreand the substituent is not an aromatic group-containing group. The upperlimit of the molecular weight of Y² is preferably 80 or less. Examplesof Y² include an alkyl group having 1 to 6 carbon atoms such as methylgroup, ethyl group, isopropyl group, tert-butyl group, and cyclohexylgroup, an alkenyl group having 2 to 6 carbon atoms such as an allylgroup, a halogen atom such as chlorine atom and bromo atom, and analkoxy group having 1 to 6 carbon atoms such as methoxy group, ethoxygroup, and cyclohexyloxy group.

n2 is preferably an integer of 0 to 2. When n2 is 1, the substituent Y²is preferably at para-position in the compound. When n2 is 2, X² ispreferably a single bond, or a hydrocarbon group having one carbon atomfrom the viewpoint of the viscosity of the composition.

The compound represented by the formula (IV) is preferably amonofunctional (meth)acrylate having one (meth)acrylate.

The molecular weight of the (meth)acrylate represented by the formula(IV) is preferably 175 to 250, more preferably 185 to 245 from theviewpoint of attainment of the low viscosity and the low volatility.

The viscosity at 25° C. of the (meth)acrylate represented by the formula(IV) is preferably 10 mPa·s or less, more preferably 6 mPa·s or less.

In addition, the compound represented by the formula (IV) preferably isused for a reaction diluent.

The amount of the compound represented by the formula (IV) to be addedis preferably 10% by mass or more, more preferably 15% by mass or more,further more preferably 20% by mass or more from the viewpoint of theviscosity of the composition and the pattern accuracy of the cured film.While the amount thereof to be added is preferably 95% by mass or less,more preferably 90% by mass or less, further more preferably 85% by massor less from the viewpoint of the tackiness of the cured film and themechanical strength of the cured film.

Specific examples of the compounds represented by Formula (IV) are shownbelow, to which, however, the present invention should not be limited.

The compound represented by the formula (V);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X³ is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y³ represents a substituent having an aromatic group and having amolecular weight of 15 or more; and n3 represents an integer of 1 to 3.

R¹ is the same as R¹ in the above formula (I) and the preferable rangethereof is the same as R¹ in the above formula (I).

X¹ is the same as Z¹ in the above and the preferable range thereof isthe same as Z¹ in the above.

Y³ represents a substituent having an aromatic group and having amolecular weight of 15 or more. Preferred embodiment of the substituenthaving an aromatic group is the embodiment that an aromatic group bondsto the aromatic ring in the formula (V) directly, or via a linkinggroup. Preferred example of the linking group thereof include analkylene group, a linking group containing a hetero atom (preferably—O—, —S—, —C(═O)O—) and a combination thereof. Among them, an alkylenegroup, —O— and a combination thereof is more preferable. The substituenthaving an aromatic group and having a molecular weight of 15 or more ispreferably a substituent having a phenyl group. Embodiment in which aphenyl group bonds to the aromatic ring in the formula (V) directly, orvia the above mentioned linking group is preferable. The substituenthaving an aromatic group and having a molecular weight of 15 or more ispreferably a phenyl group, a benzyl group, a phenoxy group, a benzyloxygroup and a phenylthio group. The molecular weight of Y³ is preferably230 to 350.

n3 is preferably 1 or 2, more preferably 1.

The amount of the compound represented by the formula (V) to be added ispreferably 10% by mass or more, more preferably 20% by mass or more,further more preferably 30% by mass or more. On the other hand, theamount thereof is preferably 90% by mass or less, more preferably 80% bymass or less, further more preferably 70% by mass, from the viewpoint ofthe tackiness and mechanical strength of the cured film.

Specific examples of the compounds represented by Formula (V) are shownbelow, to which, however, the present invention should not be limited.

The compound represented by the formula (VI);

wherein X⁶ is a (n6+1)-valent linking group; R¹ each are a hydrogenatom, an alkyl group, or a halogen atom; R² and R³ each are asubstituent; n4 and n5 each are an integer of 0 to 4; n6 is 1 or 2; andX⁴ and X⁵ each are a hydrocarbon group which may have a linking groupcontaining a hetero atom in the chain of the linking group.

X⁶ is a (n6+1)-valent linking group, preferably an alkylene group, —O—,—S—, —C(═O)O—, or a linking group consisting of a combination of two ormore thereof. The alkylene group is preferably an alkylene group having1 to 8 carbon atoms, more preferably an alkylene group having 1 to 3carbon atoms. Also, the alkylene group is preferable an unsubstitutedalkylene group.

n6 is preferably 1. When n6 is 2, the plural R¹, X⁵ and R² existing inthe formula may be the same or different.

X⁴ and X⁵ each are an alkylene group not having a linking group, morepreferably an alkylene group having 1 to 5 carbon atoms, further morepreferably an alkylene group having 1 to 3 carbon atoms, still morepreferably a methylene group.

R¹ is the same as R¹ in the above formula (I) and the preferable rangethereof is the same as R¹ in the above formula (I).

R² and R³ each represent a substituent, preferably an alkyl group, ahalogen atom, an alkoxy group, an acyl group, an acyloxy group, analkoxycarbonyl group, a cyano group, a nitro group. The alkyl group ispreferably an alkyl group having 1 to 8 carbon atoms. The halogen atomis exemplified by fluorine atom, chlorine atom, bromine atom and iodineatom, and is preferably fluorine atom. The alkoxy group is preferably analkoxy group having 1 to 8 carbon atoms. The acyl group is preferably anacyl group having 1 to 8 carbon atoms. The acyloxy group is preferablyan acyloxy group having 1 to 8 carbon atoms. The alkoxycarbonyl group ispreferably an alkoxycarbonyl group having 1 to 8 carbon atoms.

n4 and n5 each are an integer of 0 to 4. When n4 or n5 is two or more,the plural R² and R³ existing in the formula may be the same ordifferent.

The compound represented by the formula (VI) is preferably a compoundrepresented by the formula (VII);

wherein X⁶ represents an alkylene group, —O—, —S—, or a linking groupwhich is combined with two or more thereof; R¹ each are a hydrogen atom,an alkyl group, or a halogen atom.

R¹ is the same as R¹ in the above formula (I) and the preferable rangethereof is the same as R¹ in the above formula (I).

When X⁶ is an alkylene group, the alkylene group is preferably analkylene group having 1 to 8 carbon atoms, more preferably an alkylenegroup having 1 to 3 carbon atoms. The alkylene group is preferably anunsubstituted alkylene group.

X⁶ is preferably —CH₂—, —CH₂CH₂—, —O—, or —S—.

The amount of the compound represented by the formula (VI) to becontained in the composition of the present invention is not defined.However, the content relative to the total amount of the polymerizablemonomers is preferably 1 to 100% by mass, more preferably 5 to 70% bymass, further more preferably 10 to 50% by mass from the viewpoint ofthe curability and the viscosity of the composition.

Specific examples of the compounds represented by Formula (VI) are shownbelow, to which, however, the present invention should not be limited,wherein R¹ in the following is the same as R¹ in the above formula (VI),the preferable range thereof is the same as R¹ in the above formula(VI). The R¹ is more preferably a hydrogen atom.

Other Polymerizable Monomer

In the composition of the present invention, it is preferred that, inaddition to the polymerizable monomer (Ax), a polymerizable monomerother than the polymerizable monomer (Ax) is used from the viewpoint ofthe viscosity of the composition, the dry etching resistance, theimprint aptitude, and the curability.

When the other polymerizable monomer is used as well as the compoundrepresented by the formula (IV), the other polymerizable monomer ispreferably a polyfunctional polymerizable monomer, more preferably apolyfunctional (meth)acrylate, further more preferably difunctional ortrifunctional (meth)acrylate.

When the other polymerizable monomer is used as well as the compoundrepresented by the formula (V), the other polymerizable monomer ispreferably a polyfunctional polymerizable monomer, more preferably apolyfunctional (meth)acrylate, further more preferably difunctional ortrifunctional (meth)acrylate.

When the other polymerizable monomer is used as well as the compoundrepresented by the formula (VI), the other polymerizable monomer ispreferably a monofunctional polymerizable (meth)acrylate, morepreferably a monofunctional (meth)acrylate having an aromatic structureand/or an alicyclic hydrocarbon structure.

Examples of the above other polymerizable monomer include apolymerizable unsaturated monomer having 1 to 6 of ethylenic unsaturatedbond-having groups, a compound having an oxirane ring (an epoxycompound), a vinyl ether compound, a styrene derivative, a compoundhaving a fluorine atom, propenyl ether, and butenyl ether. From theviewpoint of the curability of the composition, more preferred is apolymerizable unsaturated monomer having 1 to 6 of ethylenic unsaturatedbond-having groups.

The polymerizable unsaturated monomer having from 1 to 6 of ethylenicunsaturated bond-having groups (from mono- to hexa-functionalpolymerizable unsaturated monomer) is described below.

The polymerizable unsaturated monomer having one ethylenic unsaturatedbond-having group (mono-functional polymerizable unsaturated monomer) ispreferably compounds described in JP-A-2009-73078, [0046].

Among the monofunctional polymerizable monomers having one ethylenicallyunsaturated bonds, a monofunctional (meth)acrylate compound having analicyclic hydrocarbon structure is preferably used in the presentinvention for the purpose of enhancing the dry etching resistance.Examples of the monofunctional (meth)acrylate compound having analicyclic hydrocarbon structure include dicyclopentanyl (meth)acrylate,dicyclopentanyloxyethyl (meth)acrylate, isobornyl (meth)acrylate, andadamantyl (meth)acrylate.

As the other polymerizable monomer, also preferred is a polyfunctionalpolymerizable unsaturated monomer having two ethylenic unsaturatedbond-containing groups.

The polyfunctional polymerizable unsaturated monomer having twoethylenic unsaturated bond-containing groups is preferably compoundsdescribed in JP-A-2009-73078, [0047].

Of those, preferred for use in the present invention are neopentylglycol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tripropyleneglycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate,hydroxypivalate neopentyl glycol di(meth)acrylate, and polyethyleneglycol di(meth)acrylate.

The polyfunctional polymerizable unsaturated monomer having three ormore ethylenic unsaturated bond-containing groups is preferablycompounds described in JP-A-2009-73078,

Of those, preferred for use in the present invention are EO-modifiedglycerol tri(meth)acrylate, PO-modified glycerol tri(meth)acrylate,trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropanetri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate,dipentaerythritol hexa(meth)acrylate, pentaerythritolethoxy-tetra(meth)acrylate, and pentaerythritol tetra(meth)acrylate.

Among the above-described (meth)acrylates, an acrylate compound ispreferable from the viewpoint of the curability of the composition.

The oxirane ring-having compound (epoxy compound) includes, for example,polyglycidyl esters of polybasic acids, polyglycidyl ethers ofpolyalcohols, polyglycidyl ethers of polyoxyalkylene glycols,polyglycidyl ethers of aromatic polyols, hydrogenated polyglycidylethers of aromatic polyols, urethane-polyepoxy compounds, and epoxidatedpolybutadienes. One or more of these compounds may be used either singlyor as combined.

The oxirane ring-having compound preferably used in the presentinvention is compounds described in JP-A-2009-73078,

Of those, especially preferred are bisphenol A diglycidyl ether,bisphenol F diglycidyl ether, hydrogenated bisphenol A diglycidyl ether,hydrogenated bisphenol F diglycidyl ether, 1,4-butanediol diglycidylether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether,trimethylolpropane triglycidyl ether, neopentyl glycol diglycidyl ether,polyethylene glycol diglycidyl ether, and polypropylene glycoldiglycidyl ether.

Commercial products favorable for use herein as the glycidylgroup-having compound are UVR-6216 (by Union Carbide), Glycidol, AOEX24,Cyclomer A200 (all by Daicel Chemical Industry), Epikote 828, Epikote812, Epikote 1031, Epikote 872, EpikoteCT508 (all by Yuka Shell),KRM-2400, KRM-2410, KRM-2408, KRM-2490, KRM-2720, KRM-2750 (all by AsahiDenka Kogyo), etc. One or more of these may be used either singly or ascombined.

The production method for the oxirane ring-having compounds is notspecifically defined. For example, the compounds may be produced withreference to publications of Lecture of Experimental Chemistry 20, 4thEd., Organic Synthesis II, p. 213, ff. (Maruzen, 1992); The chemistry ofheterocyclic compounds—Small Ring Heterocycles, Part 3, Oxiranes (editedby Alfred Hasfner, John & Wiley and Sons, An Interscience Publication,New York, 1985); Yoshimura, Adhesive, Vol. 29, No. 12, 32, 1985;Yoshimura, Adhesive, Vol. 30, No. 5, 42, 1986; Yoshimura, Adhesive, Vol.30, No. 7, 42, 1986; JP-A-11-100378, Japanese Patents 2906245 and2926262.

As the other polymerizable monomer for use in the present invention,vinyl ether compounds may be used in the curable composition.

Any known vinyl ether compounds are usable, including compoundsdescribed in JP-A-2009-73078, [0057].

These vinyl ether compounds can be produced, for example, according tothe method described in Stephen. C. Lapin, Polymers Paint ColourJournal, 179 (4237), 321 (1988), concretely through reaction of apolyalcohol or a polyphenol with acetylene, or through reaction of apolyalcohol or a polyphenol with a halogenoalkyl vinyl ether. One ormore of these compounds may be used either singly or as combined.

As the other polymerizable monomer for use in the present invention,styrene derivatives may also be employed. The styrene derivativesinclude, for example, styrene, p-methylstyrene, p-methoxystyrene,β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene,p-methoxy-β-methylstyrene, p-hydroxystyrene, etc.

As the other polymerizable monomer, a polymerizable compound havingfluorine atom and/or silicon atom may be also employed. Use of thepolymerizable compound having a fluorine atom and/or a silicon atomenhances the patternability. The polymerizable monomer having fluorineatom is preferably a (meth)acrylate having a perfluoroalkyl group having4 to 6 carbon atoms. Specific examples thereof include trifluoromethyl(meth)acrylate, pentafluoroethyl (meth)acrylate, (perfluorobutyl)ethyl(meth)acrylate, perfluorobutyl-hydroxypropyl (meth)acrylate,(perfluorohexyl)ethyl (meth)acrylate, octafluoropentyl (meth)acrylate,and fluorooctylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate.The polymerizable compound having silicon atom is preferably a compoundhaving a polydimethyl siloxane structure, or a trimethylsilyl structure.

The polymerizable monomer having fluorine atom and/or silicon atom maybe a polymer having a functional group having fluorine atom and/orsilicon atom and a polyfunctional group.

The amount of the polymerizable monomer having fluorine atom and/orsilicon atom to be added is preferably 0.01 to 10% by mass, morepreferably 0.1 to 8% by mass, further preferably 0.3 to 5% by mass.

As the other polymerizable monomer for use in the present invention,propenyl ethers and butenyl ethers may also be employed. Preferredexamples of the propenyl ethers or butenyl ethers include1-dodecyl-1-propenyl ether, 1-dodecyl-1-butenyl ether,1-butenoxymethyl-2-norbornene, 1,4-di(1-butenoxy)butane,1,10-di(1-butenoxy)decane, 1,4-di(1-butenoxymethyl)cyclohexane,diethylene glycol di(1-butenyl)ether, 1,2,3-tri(1-butenoxy)propane, andpropenyl ether propylene carbonate.

The amount of the above-mentioned other polymerizable monomer to beadded depends on the amount of the polymerizable monomer (Ax) used inthe present invention to be added. For example, it may be 0 to 90% bymass, preferably 5 to 80% by mass, further more preferably 20 to 80% bymass, relative to all the polymerizable compounds. In the composition ofthe present invention, two or more kinds of the polymerizable compound(Ax) may be contained.

Next described is a preferable blend embodiment of the polymerizablemonomer (Ax) in the present invention and the other polymerizablemonomer.

A monofunctional polymerizable monomer is generally used as a reactivediluent, and has an effect of lowering the viscosity of the curablecomposition of the present invention, and it is preferably added in anamount of at least 15% by mass, more preferably from 20 to 90% by mass,even more preferably from 25 to 85% by mass, and particularly preferablyfrom 30 to 80% by mass, relative to the total amount of thepolymerizable monomers in the composition. The compound represented bythe formula (IV) is preferably used as a reactive diluent.

A monomer having two polymerizable-reactive groups (difunctionalpolymerizable monomer) is added in an amount of preferably from 10 to100% by mass, more preferably from 20 to 100% by mass, and particularlypreferably from 40 to 100% by mass, relative to the total amount of allthe polymerizable monomers.

The proportion of the monofunctional and difunctional polymerizablemonomers to be added is preferably from 10 to 100% by mass, morepreferably from 30 to 100% by mass, and particularly preferably from 50to 90% by mass, relative to the total amount of the polymerizablemonomers in the composition.

The proportion of the polyfunctional polymerizable monomer having threeor more unsaturated bond-having groups is preferably at most 80% bymass, more preferably at most 60% by mass, and particularly preferablyat most 40% by mass, relative to the total amount of all thepolymerizable monomers. When the proportion of the polymerizable monomerhaving three or more polymerizable-reactive groups is at 80% by mass orless, the viscosity of the composition can be lowered, thereby itbecoming preferable.

(Photopolymerization Initiator)

The curable composition of the present invention comprises aphotopolymerization initiator. As the photopolymerization initiator inthe present invention, usable is any compound capable of generating anactive radical for polymerization of the above-mentioned polymerizablemonomer through photoirradiation. As the photopolymerization initiator,preferred are radical polymerization initiators. In the presentinvention, two or more different types of photopolymerization initiatorsmay be used, as combined.

The content of the photopolymerization initiator may be, for example,from 0.01 to 15% by mass of all the components constituting thecomposition except solvent, preferably from 0.1 to 12% by mass, morepreferably from 0.2 to 7% by mass. In case where two or more differenttypes of photopolymerization initiators are used, the total amountthereof falls within the above range.

When the content of the photopolymerization initiator is at least 0.01%by mass, then it is favorable since the sensitivity (rapid curability),the power of resolution, the line edge accuracy and the coating filmstrength of the composition tend to be better.

As the radical photopolymerization initiator for use in the presentinvention, preferred are acylphosphine oxide compounds and oxime estercompounds from the viewpoint of the curing sensitivity and theabsorption characteristics of the composition. The photopolymerizationinitiator for use in the present invention may be, for example,commercial products. Preferable examples thereof include compoundsdescribed in JP-A-2008-105414, [0091].

In the present invention, “light” includes not only those having with awavelength falling within a range of ultraviolet, near-ultraviolet,far-ultraviolet, visible, infrared, and electromagnetic waves but alsoradiations. The radiations include, for example, microwaves, electronbeams, EUV, X-rays. In addition, laser rays such as 248 nm excimerlaser, 193 nm excimer laser, 172 nm excimer laser are also usableherein. These lights may be monochromatic lights (single wavelengthlights) having passed through optical filters, or may be lights ofdifferent wavelengths (composite lights). For photoexposure, multiplephotoexposure may be employable, and for the purpose of enhancing thefilm strength and the etching resistance of the composition, entiresurface photoexposure may be effected after pattern formation.

In particular, when the composition of the present invention is used fornanoimprints, the above-described photopolymerization initiator may beused. Photopolymerizabion initiators not generating gas during the moldcompression and the photoexposure are more preferred. Gas generation, ifany, may cause mold contamination, therefore giving problems in that themold must be washed frequently, that the photocurable composition may bedeformed in the mold, and that the transferred pattern accuracy may bethereby worsened.

(Other Ingredients)

In addition to the above-mentioned polymerizable monomers and thephotopolymerization initiator, the curable composition of the presentinvention may comprise any other ingredients such as a surfactant, anantioxidant, a solvent, a polymer, a pigment, a dye and others forvarious purposes not deviating from the effect of the present invention.Preferably, the curable composition of the present invention comprisesat least one selected from a surfactant and an antioxidant.

—Surfactant—

Preferably, the curable composition of the present invention comprises asurfactant. The content of the surfactant that may be in the compositionmay be, for example, from 0.001 to 5% by mass of the composition,preferably from 0.002 to 4% by mass, more preferably from 0.005 to 3% bymass. In case where two or more different types of surfactants are inthe composition, the total amount thereof falls within the above range.When the surfactant content in the composition falls from 0.001 to 5% bymass, it is favorable from the viewpoint of the coating uniformity,therefore hardly worsening the mold transferability owing to excessivesurfactant.

As the surfactant, preferred are nonionic surfactants. More preferably,the composition comprises at least one of a fluorine-containingsurfactant, a silicone-type surfactant and a fluorine-containingsilicone-type surfactant. More preferably, the composition comprisesboth of a fluorine-containing surfactant and a silicone-type surfactant,or a fluorine-containing silicone-type surfactant. Thefluorine-containing surfactant and the silicone-type surfactant ispreferably a nonionic surfactant.

“Fluorine-containing silicone-type surfactant” as referred to hereinmeans a surfactant satisfying both the requirement of afluorine-containing surfactant and that of a silicone-type surfactant.

Using such a surfactant may solve the problem of coating failures suchas striation and flaky pattern formation (drying unevenness of resistfilm) that may occur when the curable composition of the presentinvention is applied onto substrates on which various films are formed,for example, onto silicon wafers in semiconductor production, or ontoglass square substrates, chromium films, molybdenum films, molybdenumalloy films, tantalum films, tantalum alloy films, silicon nitridefilms, amorphous silicon films, tin oxide-doped indium oxide (ITO) filmsor tin oxide films in production of liquid-crystal devices. In addition,the surfactant is effective of enhancing the flowability of thecomposition of the present invention in the cavity of a female mold, ofenhancing the mold-resist releasability, of enhancing the resistadhesiveness to substrates, and of lowering the viscosity of thecomposition. In particular, when the above-mentioned surfactant is addedto the curable composition of the present invention, the coatinguniformity of the composition can be greatly improved; and in coatingwith it using a spin coater or a slit scan coater, the compositionensures good coating aptitude irrespective of the size of the substrateto which it is applied.

The nonionic fluorine-containing surfactant preferably used in thepresent invention is those disclosed in JP-A-2009-73078, [0072].

Examples of the nonionic silicone-type surfactant include SI-10 series(Takemoto Yushi's trade name), Megafac Paintad 31 (Dai-Nippon Ink'strade name), KP-341 (Shin-Etsu Chemical's trade name).

Examples of the fluorine-containing silicone-type surfactant includeX-70-090, X-70-091, X-70-092, X-70-093 (Shin-Etsu Chemical's tradenames); Megafac R-08, XRB-4 (Dai-Nippon Ink's trade names).

—Antioxidant—

Preferably, the curable composition of the present invention comprises aknown antioxidant. The content of the antioxidant to be in thecomposition is, for example, from 0.01 to 10% by mass of the totalamount of the polymerizable monomers constituting the composition,preferably from 0.2 to 5% by mass. When two or more different types ofantioxidants are in the composition, the total amount thereof fallswithin the above range.

The antioxidant is for preventing fading by heat or photoirradiation,and for preventing fading by various gases such as ozone, activehydrogen NOx, SOx (x is an integer), etc. Especially in the presentinvention, the antioxidant added to the composition brings about theadvantage that the cured film is prevented from being discolored and thefilm thickness is prevented from being reduced through decomposition.The antioxidant includes hydrazides, hindered amine-type antioxidants,nitrogen-containing heterocyclic mercapto compounds, thioether-typeantioxidants, hindered phenol-type antioxidants, ascorbic acids, zincsulfate, thiocyanates, thiourea derivatives, saccharides, nitrites,sulfites, thiosulfates, hydroxylamine derivatives, etc. Of those,preferred are hindered phenol-type antioxidants and thioether-typeantioxidants from the viewpoint of their effect of preventing cured filmdiscoloration and preventing film thickness reduction.

Commercial products of the antioxidant usable herein include thosedisclosed in JP-A-2009-73078, [0074]. These may be used either singly oras combined.

—Polymerization Inhibitor—

Furthermore, the curable composition of the present invention preferablycomprises a polymerization inhibitor. The content of the polymerizationinhibitor is from 0.001 to 1% by mass, more preferably from 0.005 to0.5% by mass, and even more preferably from 0.008 to 0.05% by mass,relative to all the polymerizable monomers, and the change in theviscosities over time can be inhibited while maintaining a high curingsensitivity by blending the polymerization inhibitor in an appropriateamount.

—Solvent—

A solvent may be used for the curable composition of the presentinvention, in accordance with various needs. In particular, when apattern having a thickness of at most 500 nm is formed, the compositionpreferably comprises a solvent. Preferably, the solvent has a boilingpoint at normal pressure of from 80 to 200° C. Regarding the type of thesolvent, any solvent capable of dissolving the composition may be used.

Examples of the solvents include solvents having an ester structure, anketone structure, a hydroxyl group, an ether structure. Preferred amongthem are solvents having at least any one of an ester structure, aketone structure, a hydroxyl group and an ether structure in view ofevenness of a coated thin layer. Concretely, the solvent is preferablyone or more selected from propylene glycol monomethyl ether acetate,cyclohexanone, 2-heptanone, gamma-butyrolactone, propylene glycolmonomethyl ether, ethyl lactate. Most preferred is a solvent containingpropylene glycol monomethyl ether acetate as securing coatinguniformity.

The content of the solvent in the composition of the present inventionmay be suitably optimized depending on the viscosity of the constitutiveingredients except the solvent, the coatability of the composition andthe intended thickness of the film to be formed. From the viewpoint ofthe coatability, the solvent content is preferably from 0 to 99% by massof the composition, more preferably from 0 to 97% by mass. In forming apatter having a thickness of at most 500 nm, the solvent content ispreferably from 20 to 99% by mass, more preferably from 40 to 99% bymass, further more preferably from 70 to 98% by mass.

—Oligomer and Polymer Ingredient—

The composition of the present invention may comprise a polyfunctionaloligomer having a larger molecular weight than that of theabove-mentioned, other polyfunctional monomer within a range capable ofattaining the object of the present invention, for the purpose offurther increasing the crosslinking density of the composition. Examplesof the photoradical-polymerizable polyfunctional oligomer includevarious acrylate oligomers such as polyester acrylates, urethaneacrylates, polyether acrylates, epoxy acrylates. The amount of theoligomer ingredient to be added to the composition may be preferablyfrom 0 to 30% by mass of the composition except the solvent therein,more preferably from 0 to 20% by mass, even more preferably from 0 to10% by mass, most preferably from 0 to 5% by mass.

The curable composition of the present invention may comprise any otherpolymer ingredient for the purpose of enhancing the dry etchingresistance, the imprint aptitude and the curability of the composition.The polymer ingredient is preferably a polymer having a polymerizablefunctional group in the side chain thereof. The weight-average molecularweight of the polymer ingredient is preferably from 2000 to 100000, morepreferably from 5000 to 50000, from the viewpoint of the miscibility ofthe polymer with the polymerizable monomers constituting thecomposition. The amount of the polymer ingredient to be added may bepreferably from 0 to 30% by mass of the composition except the solventtherein, more preferably from 0 to 20% by mass, even more preferablyfrom 0 to 10% by mass, most preferably at most 2% by mass. When thecontent of the polymer ingredient having a molecular weight of at least2000 in the composition of the present invention is at most 30% by massof the composition except the solvent therein, then the patternabilityof the composition is bettered. From the viewpoint of the patternabilityof the composition, the resin content therein is preferably as small aspossible, and except for the surfactant and other minor additives,preferably, the composition does not comprise any additional resiningredient.

For the purpose of further enhancing the peelability, the composition ofthe present invention may comprise a release agent. Specifically, therelease agent is added for the purpose of neatly releasing a mold thatwas pressed into a layer of the composition of the present invention,without causing the roughness of surface and without leaving a residualpart of the composition of the present invention adhered on the mold.The release agent usable in the present invention may be known releaseagents including a silicone-type release agent, a solid wax such as apolyethylene wax, an amide wax, and Teflon® powder, a fluorine-typecompound, and a phosphate-type compound. Those release agents may beadhered into a mold.

The silicone-type release agent is particularly excellent in peelabilityfrom the mold when combined with the composition of the presentinvention, thereby hardly leaving a residual part of the composition ofthe present invention adhered on the mold. The silicone-type releaseagent has an organopolysiloxane structure as the base structure.Examples thereof include a unmodified or modified silicone oil, apolysiloxane having trimethyl siloxysilicate, a silicone-type acrylresin. In addition, a silicone-type leveling agent which is generallyused in a hard coating composition may be applied.

The modified silicone oil is that a polysiloxane is modified at a sidechain and/or a terminal thereof, and is divided into a reactive siliconeoil and an unreactive silicone oil. Examples of the reactive siliconeoil include an amino-modified-type silicone oil, an epoxy-modified-typesilicone oil, a carboxyl-modified-type silicone oil, acarbinol-modified-type silicone oil, a methacryl-modified-type siliconeoil, a phenol-modified-type silicone oil, a reactive at one sideterminal-type silicone oil, and a modified with different kinds offunctional groups-type silicone oil. Examples of the unreactive siliconeoil include a polyether-modified-type silicone oil, amethylstyryl-modified-type silicone oil, an alkyl-modified-type siliconeoil, a higher fatty ester-modified-type silicone oil, ahydrophilia-specially modified-type silicone oil, a higheralkoxy-modified-type silicone oil, a higher fatty acid-modified-typesilicone oil, and a fluorine-modified-type silicone oil.

Two or more modified methods are carried out to one poly siloxanemolecular.

The modified silicone oil may have a moderate compatibility withingredients of the composition. In particular, when a reactive oilhaving a reactivity with other ingredients for forming a coating filmwhich may be added into the composition is used, a problem such asadhesiveness inhibition, contamination, and degradation of the curedfilm hardly occur because the silicone oil is fixed into the cured filmof the composition of the present invention by a chemical bond. Inparticular, it is more effective of enhancing adhesiveness to adeposited layer during a deposition process. In the case of a modifiedsilicone which is modified with a functional group having aphoto-curability such as a (meth)acryloyl-modified silicone oil and avinyl-modified silicone oil, the composition after cured are excellentin various properties because of cross-link with an ingredient of thecomposition of the present invention.

The polysiloxane having trimethylsiloxysilicate is preferred because iteasily bleeds out on surface thereof, thereby being excellent inpeelability, it is also excellent in adhesiveness even if it bleeds outon surface thereof, and it is excellent in adhesiveness to ametal-deposited layer and an over coating layer.

Two or more of the release agents may be added in combination.

When the release agent is added into the composition of the presentinvention, the amount to be added is preferably 0.001 to 10% by mass ofthe total amount of the composition of the present invention, morepreferably 0.01 to 5% by mass. When the amount to be added of therelease agent is less than the above lower limit, the effect ofenhancing peelability between a mold and a layer of the curablecomposition for imprints may be insufficient. When the amount to beadded of the release agent is more than the above upper limit, there maybe a problem for roughness of the coating surface due to cissing, aproblem that adhesiveness of a substrate or a layer adjusting thesubstrate, for example a deposition layer, is damaged, or a problem thatfracture of coating film in transfer is caused (becoming too weak in thestrength of the film), therefore being not preferred.

The composition of the present invention may comprise an organic metalcoupling agent in order to enhance heat resistance of the surfacestructure having a micro-embossed pattern, strength of the surfacestructure having a micro-embossed pattern, or adhesiveness to ametal-deposited film. In addition, the organic metal coupling agent iseffective from the viewpoint of promotion of a thermal-curing reaction.Examples of the organic metal coupling agent for use in the presentinvention include a silane coupling agent, a titanium coupling agent, azirconium coupling agent, an aluminium coupling agent, and a tincoupling agent.

Examples of the silane coupling agent for use in the present inventioninclude the silane coupling agent disclosed in JP-A-2009-73078, [0083].

Examples of the titanium coupling agent for use in the present inventioninclude the titanium coupling agent disclosed in JP-A-2009-73078,[0084].

Examples of the zirconium coupling agent for use in the presentinvention include the zirconium coupling agent disclosed inJP-A-2009-73078, [0085].

Examples of the aluminium coupling agent for use in the presentinvention include the aluminium coupling agent disclosed inJP-A-2009-73078, [0086].

The organic metal coupling agent may be added in an amount of 0.001 to10% by mass of the total solid ingredient of the curable composition ofthe present invention. By adjusting the amount to be added of theorganic metal coupling agent to 0.001% by mass or more, there istendency to be more effective for enhancing the heat resistance, thestrength, and the adhesiveness to a deposited layer. By adjusting theamount to be added of the organic metal coupling agent to 10% by mass orless, there is tendency to enhance the stability of the composition andto suppress failure of the formed film.

Examples of commercial products of an ultraviolet absorber includeTinuvin P, and 234, 320, 326, 327, 328 and 213 (the above aremanufactured by Ciba-Geigy), and Sumisorb110, 130, 140, 220, 250, 300,320, 340, 350, and 400 (the above are manufactured by Sumitomo ChemicalCo., Ltd.). The ultraviolet absorber is preferably added at the ratio of0.01 to 10% by mass, relative to the total amount of the curablecomposition for imprints.

Examples of commercial products of a light stabilizer include Tinuvin292, 144, 622LD (the above are manufactured by Ciba-Geigy), SanolLS-770, 765, 292, 2626, 1114, and 744 (the above are manufactured bySankyo Chemical Industries).

The light stabilizer is preferably added at the ratio of 0.01 to 10% bymass, relative to the total amount of the curable composition forimprints.

Examples of commercial products of an antiaging agent include AntigeneW, S, P, 3C, 6C, RD-G, FR, and AW (the above are manufactured bySumitomo Chemical Co., Ltd.).

The antiaging agent is preferably added at the ratio of 0.01 to 10% bymass, relative to the total amount of the curable composition forimprints.

The composition of the present invention may comprise a plasticizer forthe purpose of adjusting the adhesiveness to a substrate, the filmpliability, the hardness. Preferred examples of the plasticizer includedioctylphthalate, didodecylphthalate, trimethyleneglycoldicaproate,dimethylglycolphthalate, tricresylphosphate, dioctyladipate,dibutylsebacate, triacetyladipate, dimethyladipate, diethyladipate,di(n-butyl)adipate, dimethylsuberate, diethylsuberate, anddi(n-butyl)suberate. The plasticizer may be arbitrarily added in anamount of 30% by mass or less in the composition, preferably 20% by massor less, more preferably 10% by mass.

The composition of the present invention may comprise an adhesionpromoter for the purpose of adjusting the adhesiveness to a substrate.Examples of the an adhesion promoter for use in the present inventioninclude benzimidazoles, poly benzimidazoles, a pyridine derivativesubstituted with a lower hydroxyalkyl group, a nitrogen-containinghetero ring compound, urea or thiourea, an organic phosphorus compound,8-oxyquinoline, 4-hydroxypteridine, 1,10-phenanthroline, 2,2′-bipyridinederivative, a benzotriazole, a phenylenediamine compound,2-amino-1-phenylethanol, N-phenylethanolamine, N-ethyldiethanolamine,N-ethyldiethanol amine, N-ethyl ethanolamine and a derivative thereof,and a benzothiazole derivative.

The adhesion promoter is preferably added in the amount of 20% by massor less, more preferably 10% by mass or less, further more preferably 5%by mass or less.

In order to acquire a more effect, the amount to be add is preferably0.1% by mass.

When the composition of the present invention is cured, a thermalpolymerization initiator may also be added if desired. Preferredexamples of the thermal polymerization initiator include peroxide and anazo compound, specifically benzoyl peroxide, andtert-butyl-peroxybenzoate, azobisisobutyronitrile.

The composition of the present invention may comprise a photobasegenerator for the purpose of adjusting a pattern form, sensitivity, etc.Examples of the photobase generator include,2-nitroglycerinebenzylcyclohexyl carbamate, triphenylmethanol,O-carbamoylhydroxylamide, O-carbamoyloxime,[[(2,6-dinitrobenzyl)oxy]carbonyl]cyclohexylamine,bis[[(2-nitrobenzyl)oxy]carbonyl] hexane 1,6-diamine,4-(methylthiobenzoyl)-1-methyl 1-zimethyl aminoprophane,N-(2-nitrobenzyloxycarbonyl)pyrrolidine, hexaamminecobalt (III) tris(triphenylmethylborate),2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone,2,6-dimethyl-3,5-diacetyl-4-(2′-nitroohenyl)-1,4-dihydropyridine,2,6-dimethyl-3,5-diacetyl-4-(2′,4′-dinitrophenyl)-1,4-dihydropyridine.

The composition of the present invention may comprise a colorant for thepurpose of improving the visibility of a coating film. As the colorant,a pigment or a dye which is used for a composition for UV ink-jet, acomposition for color filters, a composition for CCD image sensor may beused without deviating from the object of the present invention.

The pigment for use in the present invention is preferably thosedisclosed in JP-A-2008-105414, [0121]. The colorant is preferably addedin an amount of 0.001 to 2% by mass, relative to the total amount of thecomposition.

The composition of the present invention may comprise elastomerparticles for the purpose of improving the mechanical strength and thepliability.

The elastomer particles which may be added as an arbitrary ingredienthave an average particle size of 10 to 700 nm, more preferably 30 to 300nm. Examples thereof include elastomer particles of polybutadiene,polyisoprene, butadiene/acrylonitrile copolymer, styrene/butadienecopolymer, styrene/isoprene copolymer, ethylene/propylene copolymer,ethylene/alpha-olefin copolymers, ethylene/alpha-olefin/polyenecopolymer, acrylic rubber, butadiene/(meth) acrylic ester copolymer,styrene/butadiene block copolymer, or styrene/isoprene block copolymer.Further, core/shell type particles in which those elastomer particlesare coated with a methylmethacrylate polymer,methylmethacrylate/glycidylmethacrylate, or the like may be used. Theelastomer particles may have a cross-link structure.

Examples of commercial products of the elastomer particles includeResinous Bond RKB (manufactured by Resinous Chemicals), and TechnoMBS-61, MBS-69 (the above are manufactured by Techno polymer Co., Ltd.).

The elastomer particles are used singly or in combination of two or morekinds thereof. The amount of the elastomer to be added is preferably 1to 35% by mass, more preferably 2 to 30% by mass, further morepreferably 3 to 20% by mass.

The composition of the present invention may comprise a basic compoundarbitrarily for the purpose of suppressing the cure shrinkage and ofimproving the heat stability. Examples of the basic compound include anamine, a nitrogen-containing hetero ring compound such as quinoline andquinolizine, a basic alkali metal compound, and a basicalkaline-earth-metals compound. Of those, preferred is an amine from theviewpoints of the compatibility with a polymerizable monomer, andexamples of the amine include octylamine, naphthylamine, xylenediamine,benzylamine, diphenylamine, dibutylamine, dioctylamine, dimethylaniline,quinuclidine, tributylamine, trioctylamine, tetramethylethylenediamine,tetramethyl-1,6-hexamethylenediamine; hexamethylenetetramine, andtriethanolamine.

The composition of the present invention may comprise a chain transferagent for the purpose of improving the photocurability. Examples thereofinclude 4-bis(3-mercaptobutyryloxy) butane, 1,3,5-tris(3-mercaptobutyryloxyethyl) 1,3,5-triazine-2,4,6(1H,3H,5H)-trione, andpentaerythritoltetrakis (3-mercaptobutyrate).

(Viscosity)

The viscosity of all the ingredients except a solvent of the compositionof the present invention is preferably 100 mPa·s or less, morepreferably 1 to 70 mPa·s, further more preferably 2 to 5 mPa·s, stillmore preferably 3 to 30 mPa·s.

(Surface Tension)

The composition of the present invention has surface tension in therange of 18 to 30 mN/m, preferably 20 to 28 mN/m.

By adjusting it to the range, the surface smoothness is enhanced.

(Amount of Water)

The composition of the present invention preferably comprises water inan amount of 2.0% by mass or less at the time of the preparation of thecomposition, preferably 1.5% by mass or less, more preferably 1.0% bymass. By adjusting the amount of water at the time of the preparation to2.0% by mass or less, the preservability of the composition of thepresent invention becomes more stability.

(Process for Preparing)

The composition for imprints of the present invention is produced bymixing the above-mentioned ingredients. After the ingredients are mixed,the resulting mixture may be filtered through a filter having a poresize of from 0.003 μm to 5.0 μm, preferably 0.05 μm to 5.0 μm, to give asolution. The ingredients may be mixed and dissolved to prepare thecomposition, generally at a temperature falling within a range of from0° C. to 100° C. The filtration may be effected in plural stages, or maybe repeated plural times. The solution once filtered may be againfiltered. Not specifically defined, the material of the filter may beany one, for example, polyethylene resin, polypropylene resin,fluororesin, nylon resin, etc.

[Patterning Method]

The patterning method (especially micropatterning method) of using thecurable composition for imprints of the present invention is describedbelow. The patterning method of the present invention comprises applyingthe curable composition for imprints of the present invention onto asubstrate or a support (base) to form a patterning layer thereon;pressing a mold against the surface of the patterning layer; andirradiating the patterning layer with light, thereby curing thecomposition of the present invention to form a micropattern.

Here, it is preferable that the curable composition for imprints of thepresent invention is, after being irradiated with light, further heatedand cured. Concretely, the patterning layer comprising at least thecomposition of the present invention is applied onto a substrate (baseor support) and optionally dried to form a layer comprising thecomposition of the present invention (patterning layer), therebypreparing a pattern acceptor (having the patterning layer formed on thesubstrate), then a mold is pressed against the surface of the patterninglayer of the pattern acceptor to thereby transfer the mold pattern, andthe micropatterned layer is cured through photoirradiation. Thephotoimprint lithography by the patterning method of the presentinvention may enable lamination and multi-layer patterning, andtherefore, may be used in combination with an ordinary thermoimprint.

The curable composition for imprints of the present invention may form afiner micropattern at low cost and with high accuracy by a photoimprintmethod. Accordingly, the composition of the present invention can formmicropatterns heretofore formed by conventional photolithographytechnology at low cost and with high accuracy. For example, when thecomposition of the present invention is applied onto a substrate or asupport, and the layer comprising the composition is exposed to light,cured, and optionally dried (baked), it thus can be employed as apermanent film of an overcoat layer or an insulating film, and the likefor use in liquid-crystal displays (LCD); and the like, and as anetching resist for semiconductor integrated circuits, recordingmaterials, flat panel displays, or the like. In particular, the patternsformed by using the curable composition for imprints of the presentinvention are excellent in etching property, and can be preferably usedas an etching resist in dry etching using fluorocarbon, etc.

In the permanent films (resists for structural members) for use inliquid-crystal displays (LCD) and in production of semiconductor, theresist is preferably prevented from being contaminated as much aspossible with metallic or organic ionic impurities in order that theresist does not interfere with the performance of the products. Theconcentration of the metallic or organic ionic impurities in the curablecomposition for imprints of the present invention is preferably at most100 ppm, more preferably at most 1 ppm, and further more preferably atmost 10 ppb.

The patterning method (pattern transferring method) with the curablecomposition for imprints of the present invention is describedconcretely hereinunder.

In the patterning method of the present invention, the composition ofthe present invention is first applied onto a support to form apatterning layer thereon.

The coating method for applying the curable composition for imprints ofthe present invention onto a substrate may be a well known coatingmethod of, for example, a dip coating method, an air knife coatingmethod, a curtain coating method, a wire bar coating method, a gravurecoating method, an extrusion coating method, a spin coating method, aslit scanning method, an inkjet method, etc. Particularly preferred arean inkjet method and a spin coating method from the viewpoint of themold chargeability and reduction of the residual film thickness. Thethickness of the patterning method of the composition of the presentinvention may vary depending on the use thereof, and may be from 0.03 μmto 30 μm or so. The composition of the present invention may be appliedin a mode of multilayer coating. In the case where liquid drops areapplied on a substrate by an ink-jet method, the amount of the liquiddrops is preferably 1 pl to 2 pl. Between the substrate and thepatterning method of the composition of the present invention, any otherorganic layer may be formed, such as a planarizing layer, etc. Withthat, the patterning layer is not kept in direct contact with thesubstrate, and therefore, the substrate may be prevented from beingcontaminated with dust or from being scratched. The pattern to be formedof the composition of the present invention may have good adhesivenessto the organic layer, if any, formed on the substrate.

The substrate (base or support) to which the curable composition forimprints of the present invention is applied may be selected fromvarious materials depending on its use, including, for example, quartz,glass, optical film, ceramic material, vapor deposition film, magneticfilm, reflective film, metal substrate of Ni, Cu, Cr, Fe or the like,paper, SOG (spin on glass), polymer substrate such as polyester film,polycarbonate film or polyimide film, TFT array substrate, PDP electrodeplate, glass or transparent plastic substrate, electroconductivesubstrate of ITO, metal or the like, insulating substrate, semiconductorsubstrate such as silicon, silicon nitride, polysilicon, silicon oxideor amorphous silicon, which, however, are not limitative. The shape ofthe substrate is not also specifically defined. It may be tabular orroll. As described below, the substrate may be light-transmissive ornon-light-transmissive, depending on the combination thereof with amold.

Next, in the patterning method of the present invention, a mold ispressed against the surface of the patterning layer for transferring thepattern from the mold onto the patterning layer. Accordingly, themicropattern previously formed on the pressing surface of the mold istransferred onto the patterning layer.

The mold material usable in the present invention is described. IN thephotoimprint lithography with the composition of the present invention,a light-transmissive material is selected for at least one of the moldmaterial and/or the substrate. In the photoimprint lithography appliedto the present invention, the curable composition for imprints of thepresent invention is applied onto a substrate to form a patterning layerthereon, and a light-transmissive mold is pressed against the surface ofthe layer, then this is irradiated with light from the back of the moldand the patterning layer is thereby cured. Alternatively, the curablecomposition for photoimprints is applied onto a light-transmissivesubstrate, then a mold is pressed against it, and this is irradiatedwith light from the back of the substrate whereby the curablecomposition for photoimprints can be cured.

The photoirradiation may be attained while the mold is kept in contactwith the layer or after the mold is released. In the present invention,preferably, the photoirradiation is attained while the mold is kept incontact with the patterning layer.

The mold usable in the present invention has a transferable patternformed thereon. The pattern of the mold may be formed, for example,through photolithography, electronic beam lithography or the like bywhich a pattern may be formed to a desired processing accuracy. In thepresent invention, however, the mold patterning method is notspecifically defined.

Not specifically defined, the light-transmissive mold material for usein the present invention may be any one having a desired strength anddurability. Concretely, its examples include glass, quartz,light-transparent resin such as PMMA or polycarbonate resin, transparentmetal deposition film, flexible film of polydimethylsiloxane or thelike, photocured film, metal film, etc.

The non-light-transmissive mold to be used in the present inventionwhere a light-transmissive substrate is used is not also specificallydefined and may be any one having a predetermined strength. Concretely,examples of the mold material include ceramic material, deposition film,magnetic film, reflective film, metal material of Ni, Cu, Cr, Fe or thelike, as well as SiC, silicon, silicon nitride, polysilicon, siliconoxide, amorphous silicon, etc. However, these are not limitative. Theshape of the mold is not also specifically defined, and may be any of atabular mold or a roll mold. The roll mold is used especially whencontinuous transfer in patterning is desired.

The mold for use in the patterning method of the present invention maybe processed for surface release treatment for the purpose of enhancingthe releasability of the curable composition for imprint of the presentinvention from the mold. The mold of the type includes thosesurface-treated with a silicone-type or fluorine-containing silanecoupling agent, for which, for example, commercial release agents suchas Daikin's Optool DSX, Sumitomo 3M's Novec EGC-1720 and others arepreferred.

In photoimprint lithography with the composition of the presentinvention, in general, the mold pressure in the patterning method of thepresent invention is preferably at most atmospheres. When the moldpressure is at most 10 atmospheres, then the mold and the substrate arehardly deformed and the patterning accuracy tends to increase. It isalso favorable since the pressure unit may be small-sized since thepressure to be given to the mold may be low. The mold pressure ispreferably selected from the region capable of securing the moldtransfer uniformity, within a range within which the residual film ofthe curable composition for imprints in the area of mold patternprojections may be reduced.

In the patterning method of the present invention, the dose ofphotoirradiation in the step of irradiating the patterning layer withlight may be sufficiently larger than the dose necessary for curing. Thedose necessary for curing may be suitably determined depending on thedegree of consumption of the unsaturated bonds in the curablecomposition for imprints and on the tackiness of the cured film aspreviously determined.

In the photoimprint lithography applied to the present invention, thesubstrate temperature in photoirradiation may be room temperature;however, the photoirradiation may be attained under heat for enhancingthe reactivity. In the previous stage of photoirradiation, preferably,the system is kept in vacuum as effective for preventing contaminationwith bubbles or contamination with oxygen or for preventing thereduction in reactivity, and as effective for enhancing the adhesivenessof the curable composition for imprints with mold. The system may besubjected to photoirradiation while still kept in vacuum. In thepatterning method of the present invention, the vacuum degree inphotoirradiation is preferably from 10⁻¹ Pa to ordinary pressure.

Light to be used for photoirradiation to cure the curable compositionfor imprints of the present invention is not specifically defined. Forexample, it includes light and irradiations with a wavelength fallingwithin a range of high-energy ionizing radiation, near-ultraviolet,far-ultraviolet, visible, infrared, etc. The high-energy ionizingradiation source includes, for example, accelerators such as Cockcroftaccelerator, Handegraf accelerator, linear accelerator, betatoron,cyclotron, etc. The electron beams accelerated by such an acceleratorare used most conveniently and most economically; but also are any otherradioisotopes and other radiations from nuclear reactors, such as γrays, X rays, α rays, neutron beams, proton beams, etc. The UV sourcesinclude, for example, UV fluorescent lamp, low-pressure mercury lamp,high-pressure mercury lamp, ultra-high-pressure mercury lamp, xenonlamp, carbon arc lamp, solar lamp, etc. The radiations includemicrowaves, EUV, etc. In addition, laser rays for use in microprocessingof semiconductors, such as LED, semiconductor laser ray, 248 nm KrFexcimer laser ray, 193 nm ArF excimer laser ray and others, are alsofavorably used in the present invention. These lights may bemonochromatic lights, or may also be lights of different wavelengths(mixed lights).

In photoexposure, the light intensity is preferably within a range offrom 1 mW/cm² to 50 mW/cm². When the light intensity is at least 1mW/cm², then the producibility may increase since the photoexposure timemay be reduced; and when the light intensity is at most 50 mW/cm², thenit is favorable since the properties of the permanent film formed may beprevented from being degraded owing to side reaction. Also preferably,the dose in photoexposure is within a range of from 5 mJ/cm² to 1000mJ/cm². When the dose is less than 5 mJ/cm², then the photoexposuremargin may be narrow and there may occur problems in that thephotocuring may be insufficient and the unreacted matter may adhere tomold. On the other hand, when the dose is more than 1000 mJ/cm², thenthe composition may decompose and the permanent film formed may bedegraded.

Further, in photoexposure, the oxygen concentration in the atmospheremay be controlled to be less than 100 mg/L by introducing an inert gassuch as nitrogen or argon into the system for preventing the radicalpolymerization from being retarded by oxygen.

In the patterning method of the present invention, after the patternlayer is cured through photoirradiation, if desired, the cured patternmay be further cured under heat given thereto. The method mayadditionally includes the post-curing step. Thermal curing of thecomposition of the present invention after photoirradiation ispreferably attained at 150 to 280° C., more preferably at 200 to 250° C.The heating time is preferably from 5 to 60 minutes, more preferablyfrom 15 to 45 minutes.

[Pattern]

The pattern thus formed according to the patterning method of thepresent invention as described in the above can be used as a permanentfilm for use in liquid-crystal displays (LCD) and others, or as anetching resist. After its production, the permanent film may be bottledin a container such as a gallon bottle or a coated bottle, and may betransported or stored. In this case, the container may be purged with aninert gas such as nitrogen, argon or the like for preventing thecomposition therein from being degraded. The composition may betransported or stored at ordinary temperature, but for preventing thepermanent film from being degraded, it is preferably transported orstored at a controlled temperature of from −20° C. to 0° C.Needless-to-say, the composition is shielded from light to such a levelon which its reaction does not go on.

The pattern of the present invention formed by the patterning method ofthe present invention is also useful as an etching resist. In caseswhere the pattern of the present invention is used as an etching resist,a nano-order micropattern is first formed on a substrate such as asilicon wafer with a thin film of SiO₂ or the like formed thereon,according to the patterning method of the present invention. Next, byetching it with an etching gas, such as hydrogen fluoride, or the likein case of wet etching or CF₄, or the like in case of dry etching, adesired pattern can be formed on the substrate. The curable compositionfor imprints is particularly excellent in resistance to dry etching.

EXAMPLES

The characteristics of the present invention are described moreconcretely with reference to Production Examples and Examples givenbelow. In the following Examples, the material used, its amount and theratio, the details of the treatment and the treatment process may besuitably modified or changed not overstepping the scope of the presentinvention. Accordingly, the present invention should not be limitativelyinterpreted by the Examples mentioned below.

Example 1 Synthesis of R-1-1-R-1-7

Monofunctional acrylate monomers R-1-1-R-1-7 shown in the table belowwere synthesized by acrylizing alcohol as the precursor thereof and bypurifying it with silica gel-column chromatography.

<Other Monofunctional Monomers>

R-1-8: benzyl acrylate (Biscoat #160, manufactured by Osaka OrganicChemical Industry Ltd.)R-1-9: 2-ethylhexyl acrylate (manufactured by NIPPON SHOKUBAI)R-1-10: cyclohexylethyl acrylate (the alcohol as the precursor thereofwas acrylized to synthesize it.)R-1-11: dicyclopentenyl acrylate (FANCRYL FA-513A, manufactured byHitachi Chemical)

<Measurement of Molecular Weight of Monomer>

Molecular weight of the monomers was computed with CS Chem Draw Drawing.

<Measurement of Viscosity of Monomer>

The measurement of viscosity of the monomers R-1-1-R-1-7 was conductedat 25±0.2° C. using a RE-80 L-type rotational viscometer manufactured byToki Sangyo Co., Ltd.

The measurement of the viscosity was conducted, respectively, by settingthe rotation speed in the measurement at 100 rpm in the case of 0.5mPa·s or more and less than 5 mPa·s, at 50 rpm in the case of 5 mPa·s ormore and less than 10 mPa·s, at 20 rpm in the case of 10 mPa·s or moreand less than 30 mPa·s, at 10 rpm in the case of 30 mPa·s or more andless than 60 mPa·s, at 5 rpm in the case of 60 mPa·s or more and lessthan 120 mPa·s, and at 1 rpm or 0.5 rpm in the case of 120 mPa·s ormore. The viscosity ranges were classified and evaluated as follows;

A: less than 6 mPa·sB: not less than 6 mPa·s to less than 10 mPa·sC: not less than 10 mPa·s

<Measurement of Volatility of Monomer>

0.5 g of each R-1-1 to R-1-11 was weighed, and spread on an aluminumcup. Each weight residual ratio [%] of R-1-1 to R-1-11 after holding for5 minutes under decompression of less than 0.2 Torr was measured. Theresult was classified as follows;

A: the residual ratio was in the range of not less than 95%.B: the residual ratio was in the range of not less than 90% to less than95%.C: the residual ratio was in the range of less than 90%.

TABLE 1

Monomer R-1-1 R-1-2 R-1-3 R-1-4 Molecular 190 204 190 192 weightViscosity A A A A Volatility A A A A

Monomer R-1-5 R-1-6 R-1-7 Molecular weight 241 188 255 Viscosity A A BVolatility A B A

TABLE 2 Monomer R-1-8 R-1-9 R-1-10 R-1-11 Molecular 162 184 182 206weight Viscosity A A A C Volatility C C C A

<Two-Functional Monomer>

S-1: neopentyl glycol diacrylate (manufactured by Nipponkayaku)S-2: acrylate-2-acryloyloxy-3-aryloxy-propyl ester

The compound was synthesized by the following method.

500 g of aryl glycidyl ether (manufactured by Tokyo Chemicals, A0221),and 331.5 g of acrylic acid (manufactured by Tokyo Chemicals, A0141)were reacted under 14.0 g of tetra-n-butyl ammonium bromide (TokyoChemicals, T0054). To the reacted product, 570.5 g of triethyl amine(manufactured by Wako Pure Chem., 202-02046) and 471.0 g of acrylic acidchloride (manufactured by Tokyo Chemicals, A0147) were added to obtaincrude product of S-2. The obtained crude product was purified bydistillation under reduced pressure (3.7 mmHg, 125° C.) to obtain 656 gof S-2.

<Three-Functional Monomer>

T-1: trimethylolpropane triacrylate (Aronix M-309, manufactured byToagosei)

<Antioxidant>

A-1: Sumilizer GA80 (manufactured by Sumitomo Chemical Co., Ltd.,hindered phenol-type)A-2: Adecastab A0503 (manufactured by Adeka, thioether-type)A-3: Irganox1035FF (manufactured by Ciba, hinderedphenol-type+thioether-type)A-4: Adecastab LA-57 (manufactured by Adeka Japan, hindered amine-type)A-5: TINUVIN144 (manufactured by Ciba, hindered amine-type+hinderedphenol-type)

<Photopolymerization Initiator>

P-1: 2,4,6-trimethylbenzoyl-ethoxy phenyl-phosphine oxide(Lucirin TPO-L,manufactured by BASF)

<Nonionic Surfactant>

W-1-1: nonionic surfactant (manufactured by Takemoto Oil, Pionin D6315)W-1-2: fluorine-containing surfactant (manufactured by DIC Inc. MEGAFACEF780F)

Example 1-1

The polymerizable monomer of R-1-1 (40% by mass), the polymerizablemonomer of S-1 (30% by mass), the polymerizable monomer T-1 (30% bymass), the photopolymerization initiator of P-1 (0.5% by mass %,relative to the amount of the total amount of the polymerizablemonomers), the antioxidant of A-1 (1.5% by mass, relative to the totalamount of the polymerizable monomers), the antioxidant of A-2 (0.5% bymass, relative to the total amount of the polymerizable monomers), thesurfactant of W-1-1 (0.1% by mass, relative to the total amount of thepolymerizable monomers) and the surfactant of W-1-2 (0.04% by mass,relative to the total amount of the polymerizable monomers) were mixedto prepare the curable composition for imprints of Example 1-1.

(Curing with Photo Irradiation)

The compositions was applied onto a grass substrate in a mode of spincoating to obtain a coating film having a thickness of 3.0 micrometers.The spin-coating film was set to an imprinting device manufactured byORC, which has a high-pressure mercury vapor lamp as an optical source(the lump power was 2000 mW/cm²). Then, a mold having a line/spacepattern with a line width of 10 micrometers and having a groove depth of4.0 micrometers, of which material was polydimethylsiloxane (that wasobtained by curing SILPOT184 manufactured by TORAY/Dow Corning at 80°C., for 60 min.), was used. After setting the inside of the device intoa vacuum (the degree of vacuum was 10 Torr, about 1.33 kPa (s)), themold was pressed against the substrate, and then nitrogen was introducedto the device by conducting the nitrogen purging (1.5 atm: moldpressure). The mold was exposed to light at a luminance of 10 mW/cm² anda light exposure dose of 240 mJ/cm² from the back of the mold. After theexposure, the mold was released to give a resist pattern.

(Curing by Heating)

The resist pattern obtained by the above-mentioned method was heated at230° C. for 30 minutes in oven to completely be cured.

Examples 1-2 to 1-7

Each of curable compositions for imprints of Examples 1-2 to 1-7 asdescribed in the table below was prepared. Each resist pattern wasobtained by curing the composition with photo irradiation and with heatas the same method in Example 1-1.

Comparative Example 1-1

In the same manner as in Example 1-1 except that R-1-1 was changed intoR-1-8, a composition of Comparative Example 1-1 was prepared and wascured with photo irradiation and with heat to obtain a resist pattern.

Comparative Example 1-2

In the same manner as in Example 1-1 except that R-1-1 was changed intoR-1-9, a composition of Comparative Example 1-2 was prepared and wascured with photo irradiation and with heat to obtain a resist pattern.

Comparative Example 1-3

In the same manner as in Example 1-1 except that R-1-1 was changed intoR-1-10, a composition of Comparative Example 1-3 was prepared and wascured with photo irradiation and with heat to obtain a resist pattern.

Comparative Example 1-4

In the same manner as in Example 1-1 except that R-1-1 was changed intoR-1-11, a composition of Comparative Example 1-4 was prepared and wascured with photo irradiation and with heat to obtain a resist pattern.

The compositions of Examples and Comparative Examples are shown below.

TABLE 3 Example 1-1 Example 1-2 Example 1-3 Example 1-4 Example 1-5Example 1-6 Example 1-7 Com- Com- Com- Com- Com- Com- Com- pound Contentpound Content pound Content pound Content pound Content pound Contentpound Content Polymerizable R-1-1 40 R-1-2 30 R-1-3 25 R-1-4 35 R-1-5 45R-1-6 30 R-1-7 40 monomer S-1 30 S-1 40 S-1 15 S-2 35 S-1 25 S-1 40 S-130 T-1 30 T-1 30 S-2 40 T-1 30 S-2 10 T-1 30 T-1 30 T-1 20 T-1 20 Photo-P-1 0.5 P-1 1 P-1 0.5 P-1 0.5 P-1 0.5 P-1 0.5 P-1 0.5 polymerizableinitiator Antioxidant A-1 1.5 A-1 1.5 A-1 1.5 A-4 2 A-5 2 A-1 1.5 A-11.5 A-2 0.5 A-2 0.5 A-3 0.5 A-2 0.5 A-2 0.5 Surfactant W-1-1 0.1 W-1-10.1 W-1-1 0.1 W-1-1 0.1 W-1-1 0.1 W-1-1 0.1 W-1-1 0.1 W-1-2 0.04 W-1-20.04 W-1-2 0.04 W-1-2 0.04 W-1-2 0.04 W-1-2 0.04 W-1-2 0.04

TABLE 4 Comparative Comparative Comparative Comparative Example 1-1Example 1-2 Example 1-3 Example 1-4 Compound Content Compound ContentCompound Content Compound Content Polymerizable R-1-8 40 R-1-9 40 R-1-1040 R-1-11 40 monomer S-1 30 S-1 30 S-1 30 S-1 30 T-1 30 T-1 30 T-1 30T-1 30 Photopolymerizable P-1 0.5 P-1 0.5 P-1 0.5 P-1 0.5 initiatorAntioxidant A-1 1.5 A-1 1.5 A-1 1.5 A-1 1.5 A-2 0.5 A-2 0.5 A-2 0.5 A-20.5 Surfactant W-1-1 0.1 W-1-1 0.1 W-1-1 0.1 W-1-1 0.1 W-1-2 0.04 W-1-20.04 W-1-2 0.04 W-1-2 0.04

<Evaluation>

Each of the compositions of Examples and Comparative Examples wasmeasured and evaluated in accordance with the following evaluationmethod.

<Measurement of Viscosity of Composition>

The measurement of the viscosity of the composition (before cured) wasconducted at 25±0.2° C. using a RE-80 L-type rotational viscometermanufactured by Toki Sangyo Co., Ltd.

The measurement of the viscosity was conducted, respectively, by settingthe rotation speed in the measurement at 100 rpm in the case of 0.5mPa·s or more and less than 5 mPa·s, at 50 rpm in the case of 5 mPa·s ormore and less than 10 mPa·s, at 20 rpm in the case of 10 mPa·s or moreand less than 30 mPa·s, and at 10 rpm in the case of 30 mPa·s or moreand less than 60 mPa·s. The viscosity ranges were classified andevaluated as follows;

A: less than 10 mPa·sB: not less than 10 mPa·s to less than 14 mPa·sC: not less than 14 mPa·s

<Observation of Pattern Accuracy>

Shape of the resist pattern formed in the above was observed using ascanning electromicroscope or optical microscope. The pattern wasclassified and evaluated as follows;

A: A pattern is almost the same as the original pattern which forms apattern of the mold.

B: A pattern has a different part from the original pattern which formsa pattern of the mold (in the range of less than 10%).

C: A pattern has a different part from the original pattern which formsa pattern of the mold (in the range of not less than 10% to less than20%).

D: A pattern is completely different from the original pattern whichforms a pattern of the mold, or has a different part from the originalpattern which forms a pattern of the mold (in the range of not less than20%).

<Dry Etching Resistance>

The curable composition for imprints as prepared above was applied ontoan Si wafer, and then while not pressed against a mold, this was exposedto light in a nitrogen atmosphere at a light exposure dose of 240mJ/cm². Using a dry etcher (U-621) manufactured by HitachiHigh-Technology, this was dry-etched with plasma of a gas ofAr/C₄F₆/O₂=100:4:2, the residual film amount was measured, and theetching rate per second was computed. The resulting etching rate wasstandardized, based on the value, 1, in Comparative Example 1-1. Bycomparison thereto, Examples and Comparative Examples were evaluated.The smaller values indicate better dry etching resistance.

The measurement results are shown in the table below.

TABLE 5 Viscosity Pattern accuracy Dry etching resistance Example 1-1 AA 0.8 Example 1-2 A A 0.8 Example 1-3 A A 0.8 Example 1-4 A A 0.9Example 1-5 A A 0.9 Example 1-6 A A 0.95 Example 1-7 B B 0.95Comparative A C 1.0 Example 1-1 Comparative A D 1.2 Example 1-2Comparative A C 1.1 Example 1-3 Comparative C C 1.0 Example 1-4

Examples 1-1 to 1-7 showed good results for the viscosity of thecomposition and for the pattern accuracy after cured. ComparativeExamples 1-1 to 1-3 were poor in the pattern accuracy while theviscosity of the composition was low-level similar to the composition ofthe present invention. It would appear that a part of diluent havinghigh volatility is volatilized after the liquid was coated before thepattern was formed, and therefore, the viscosity of the residualcomposition rises. Compared with the composition of the presentinvention, the composition in Comparative Example 1-4 had higherviscosity, and was poor in the pattern accuracy. It was found that acomposition for imprints excellent in the viscosity and the patternaccuracy was obtained by using the polymerizable monomer (Ax).

Example 2 Synthesis Example 1 Synthesis of Polymerizable Monomer I-1

100 ml of 25% hydrobromic acid/acetic acid solution were added to 30 gof diphenyl ether and 21.2 g of paraformaldehyde to react it at 50° C.for 3 hours. To this, 100 ml of 25% hydrobromic acid/acetic acidsolution was added to react it for 3 hours. To the reaction liquid, icewas added to obtain a solid. The solid was dissolved in acetone, andwater was further added to it. This was filtrated to remove powders andwas washed with water. This was washed with methanol and dried to obtain30 g of 4,4′-bis bromomethyl phenyl ether. To this, 300 ml ofN-methylpyrrolidone, 35 g of potassium carbonate, and 18 g of acrylicacid were added to react it at 50° C. for 3 hours. This was extractedwith acetic ether, and then, the organic phase thereof was washed withwater, dried and concentrated to obtain crude product. 23 g of thepolymerizable monomer I-1 was obtained by refining the crude product bycolumn chromatography.

The polymerizable monomer I-1 was liquid at 25° C., and has a viscosityof 63 mPa·s at 25° C.

¹H-NMR (CDCl₃): delta 5.2 (s, 4H), delta 5.85 (d, 2H), delta 6.2 (dd,2H), delta 6.45 (d, 2H), delta 7.0 (d, 4H), delta 7.4 (d, 4H)

Synthesis Example 2 Synthesis of Polymerizable Monomer I-2

52 ml of 85% phosphoric acid solution and 100 ml of 30% hydrobromicacid/acetic acid solution were added to 21.5 g of diphenyl methane and20 g of paraformaldehyde to react it at 110° C. for 6 hours.

After cooled, the precipitated solid was washed with water, reslurriedwith acetone and dried to obtain 16 g of 4,4′-bis bromomethyl diphenylmethane. To this, 150 ml of N-methylpyrrolidone, 18 g of potassiumcarbonate, and 9 g of acrylic acid were added to react it at 60° C. for2 hours. To the reaction liquid, 500 ml of water was added. This wasextracted with acetic ether, and then, the organic phase thereof waswashed with water, dried and concentrated to obtain crude product. 15 gof the polymerizable monomer I-2 was obtained by refining the crudeproduct by column chromatography.

The polymerizable monomer I-2 was liquid at 25° C.

¹H-NMR (CDCl₃): delta 4.0 (s, 2H), delta 5.2 (s, 4H), delta 5.85 (d,2H), delta 6.2 (dd, 2H), delta 6.45 (d, 2H), delta 7.2 (d, 4H), delta7.3 (d, 4H)

Synthesis Example 3

Each of the polymerizable monomers I-3 and I-4 was synthesized by asimilar method to that in the above-mentioned Synthesis Example 1.

(Preparation of Curable Composition)

To the polymerizable monomer descried below in the table, thepolymerizable initiator P-1 which is the same as that in Example 1 (2%by mass), the following surface surfactant W-2-1 (0.1% by mass), thefollowing surface surfactant W-2-2 (0.04% by mass), the followingantioxidant A-1 which is the same as that in Example 1 (1% by mass), andthe antioxidant A-2 which is the same as that in Example 1 (1% by mass)were added. Further, as a polymerizable prohibitior, 4-methoxyphenol wasadded to be set to 200 ppm, relative to the polymerizable monomer. Thiswas filtered with a 0.1-micrometer filter made of tetrafluoroethylene toprepare the curable composition.

TABLE 6 Polymerizable monomer (Ax) Other polymerizable monomer Example2-1 I-1 (80) R-2-1 (20) Example 2-2 I-2 (80) R-2-1 (20) Example 2-3 I-3(20) R-2-1 (80) Example 2-4 I-4 (20) R-2-1 (80) Example 2-5 I-2 (50)R-2-2 (50) Example 2-6 I-2 (50) R-2-5 (50) Comparative — R-2-1 (20)R-2-3 (80) Example 2-1 Comparative — R-2-1 (20) R-2-4 (80) Example 2-2<Polymerizable monomer (Ax)>

<Other Polymerizable monomer> R-2-1: benzylacrylate (Biscoat #160:manufactured by Osaka Organic Chemical Industry Ltd.) R-2-2: 1-naphtymethylacrylate R-2-3: tetraethylene glycol diacrylate (V#335HP:manufactured by Osaka Organic Chemical Industry Ltd.) R-2-4: ethoxylatedbisphenol A diacrylate (NK Ester A-BPE-10: manufactured by Shin-nakamuraChemical corporation) R-2-5: 2-ethylhexyl acrylate (manufactured byAldrich)

(Evaluation)

The following evaluations were performed for each of the obtainedcurable compositions. The results were shown in Table 2.

<Photocurability of Curable Compositon>

The prepared curable composition as prepared above was applied onto a Siwafer, and then, while not pressed against a mold, this was exposed tolight in a nitrogen atmosphere at a light exposure dose of 240 mJ/cm².All of the obtained light-exposed films were tack-free and were goodcured films.

<Dry Etching Resistance>

The curable composition for imprints as prepared above was applied ontoan Si wafer, and then, while not pressed against a mold, this wasexposed to light in a nitrogen atmosphere at a light exposure dose of240 mJ/cm². Using a dry etcher (U-621) manufactured by HitachiHigh-Technology, this was dry-etched with plasma of a gas ofAr/C₄F₆/O₂=100:4:2, the residual film amount was measured, and theetching rate per second was computed. The resulting etching rate wasstandardized, based on the value, 1 in Comparative Example 2-1. Bycomparison thereto, Examples and Comparative Examples were evaluated.The smaller values indicate better dry etching resistance.

<Evaluation of Patternability>

Each of the compositions as prepared above was applied onto a siliconesubstrate in a mode of spin coating. On the resulting film, a mold ofquartz having a rectangular line/space pattern (1/1) with a line widthof 100 nm and a groove thickness of 100 nm, of which the surface hadbeen processed with fluorine, was put, and set into a imprinting device.The device was degassed in a vacuum, and then nitrogen was introduced tothe device by conducting nitrogen purging. The mold was pressed againstthe substrate under a pressure of 0.5 MPa at 25° C., and then this wasexposed to light under a condition of 240 mJ/cm² from the back of themold. After the exposure, the mold was released to give a pattern. Itwas checked with a scanning electromicroscope and an optical microscopeas to whether or not the pattern transfer defects were present or absenttherein due to the foreign bodies, and evaluation was conducted in thesame manner as below.

A: A rectangular pattern substantially complementary to the mold wasobtained.

B: The pattern top was roundish.

C: The pattern top was roundish, and the height of the pattern was low.

TABLE 7 Dry etching resistance Patternability Example 2-1 0.48 A Example2-2 0.48 A Example 2-3 0.50 A Example 2-4 0.50 A Example 2-5 0.45 AExample 2-6 0.55 A Comparative 1.0 A Example 2-1 Comparative 0.65 CExample 2-2

Examples 2-1 to 2-6 in which the polymerizable monomer in the presentinvention were excellent in the dry etching resistance and thepatternability. In particular, Examples 2-1 to 2-5 were more excellentin the dry etching resistance. Comparative Example 2-1 in which thepublicly known polymerizable monomer was used, was poor in the dryetching resistance. Comparative Example 2-2 was poor in both of the dryetching resistance and the patternability. In particular, even if acompound which is similar to the compound used in the present inventionis used, the effect thereof was remarkably different from the effect ofthe present invention.

Example 3 Synthesis Synthesis of 3-phenoxybenzyl acrylate (V-1)

25 g of 3-phenoxy benzyl acrylate was dissolved in 300 ml of acetone,and further 16.4 g of triethylamine and 0.1 g of N,N-dimethylaminopyridine were added. To this, 12.5 g of acrylic acid chloride was addedunder ice-cold condition, to react it at a room temperature for 2 hours.After adding water and agitating for 30 minutes, this was extracted withethyl acetate, and the organic phase thereof was wished with dilutehydrochloric acid solution, NaHSO₃ solution, and water. The organicphase was dried and concentrated to obtain 29 g of 3-phenoxybenzylacrylate. It was liquid at 25° C., and had a viscosity of 14.5 mPa·s at25° C.

Synthesis of 4-acyloxy methyl diphenylmethane (V-2)

6.3 g of 4-bromomethyldiphenylmethane was dissolve in 100 ml ofacetonitrile, and 2.3 g of acrylic acid and 5.0 g of potassium carbonatewere added to react it for 3 hours at 70° C. To the reaction liquid,ethyl acetate was added, washed with water, dried and concentrated toobtain 4.3 g of 4-acryloxymethyl diphenylmethane. It was liquid at 25°C., and had a viscosity of 1.9 mPa·s at 25° C.

Synthesis of 4-benxyloxy benzyl acrylate (V-3)

It was synthesized by a similar method to that of 3-phenoxy benzylacrylate. It was liquid at 25° C., and had a viscosity of 25.4 mPa·s at25° C.

(Preparation of Curable Composition)

To the polymerizable monomer descried below in the following Table 8,the polymerizable initiator P-1 which is the same as that in Example 1(2% by mass), the surface surfactant W-2-1 (0.1% by mass), the surfacesurfactant W-2-2 (0.04% by mass), the antioxidant A-1 which is the sameas that in Example 1 (1% by mass), the antioxidant A-2 which is the sameas that in Example 1 (1% by mass) and perfluorohexyl ethyl acrylate (1%by mass) were mixed. Further, as a polymerizable prohibitior,4-methoxyphenol was added to be set to 200 ppm, relative to thepolymerizable monomer. This was filtered with a 0.1-micrometer filtermade of tetrafluoroethylene to prepare the curable composition.

TABLE 8 Polymerizable monomer (Ax) Other polymerizable monomer Example3-1 V-1 (80) T-1 (20) Example 3-2 V-2 (80) T-1 (20) Example 3-3 V-3 (80)T-1 (20) Example 3-4 V-1 (50) R-3-2 (50) Example 3-5 V-2 (50) R-3-2 (50)Example 3-6 V-3 (50) R-3-2 (50) Comparative — T-1 (20) R-3-1 (80)Example 3-1 Comparative — R-3-2 (50) R-3-1 (50) Example 3-2 <OtherPolymerizable Monomer> T-1: trimethylolpropane triacrylate (AronixM-309: manufactured by Toa Gosei Co., Ltd.) R-3-1: benzyl acrylate(Biscoat #160: manufactured by Osaka Organic Chemical Industry Ltd.)R-3-2: tricyclodecane dimethanol diacrylate

Evaluation for the dry etching resistance and the patternability foreach of the obtained Examples and Comparative Examples was measuredaccording to the same method as that in Example 2. The resulting etchingrate was standardized, based on the value, 1 in Comparative Example 3-1.By comparison thereto, Examples and Comparative Examples were evaluated.The smaller values indicate better dry etching resistance. The resultsare shown at the following Table 9.

TABLE 9 Dry etching resistance Patternability Example 3-1 0.60 A Example3-2 0.61 A Example 3-3 0.61 A Example 3-4 0.50 A Example 3-5 0.51 AExample 3-6 0.51 A Comparative 1.0 C Example 3-1 Comparative 0.80 BExample 3-2

INDUSTRIAL APPLICABILITY

The curable composition for imprints of the present invention may beapplicable to various imprint techniques. In particular, it ispreferably for use in a curable composition for forming a nano-sizemicropattern. Specifically, the composition of the present invention isfor use in micropatterning to give imprints, which is used in producingmagnetic recording media such as semiconductor integrated circuits, flatscreens, microelectromechanical systems (MEMS), sensor devices, opticaldiscs, high-density memory discs, etc.; optical members such asgratings, relief holograms, etc.; optical films for production ofnanodevices, optical devices, flat panel displays, etc.; polarizingelements, thin-film transistors in liquid-crystal displays, organictransistors, color filters, overcoat layers, pillar materials, ribmaterials for liquid-crystal alignment, microlens arrays, immunoassaychips, DNA separation chips, microreactors, nanobio devices, opticalwaveguides, optical filters, photonic liquid crystals, etc.

The present disclosure relates to the subject matter contained inJapanese Patent Application No. 308838/2008 filed on Dec. 3, 2008,Japanese Patent Application No. 5590/2009 filed on Jan. 14, 2009, andJapanese Patent Application No. 176416/2009 filed on Jul. 29, 2009,which are expressly incorporated herein by reference in their entirety.

1. A curable composition for imprints comprising a polymerizable monomer(Ax) and a photopolymerization initiator, wherein the polymerizablemonomer (Ax) is represented by the following formula (I);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; Z is a group having an aromatic group and having a molecularweight of 100 or more; and, when the polymerizable monomer (Ax) isliquid at 25° C., the polymerizable monomer (Ax) has a viscosity of 500mPa·s or less.
 2. The curable composition for imprints according toclaim 1, wherein Z in the formula (I) represents —Z¹—Z²; wherein Z¹ is asingle bond, or a hydrocarbon group which may have a linking groupcontaining a hetero atom in the chain of the linking group; Z² is anaromatic group having a molecular weight of 90 or more; and Z² may havea substituent.
 3. The curable composition for imprints according toclaim 1, wherein the polymerizable monomer (Ax) is a compoundrepresented by the following formula (II);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X¹ is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y¹ represents a substituent having a molecular weight of 15 ormore; n1 represents an integer of 0 to 3; when n1 is 0, X¹ is ahydrocarbon group having two or more carbon atoms; and Ar is a phenylenegroup, or an aromatic group having two or more aromatic rings bonded toeach other in series.
 4. The curable composition for imprints accordingto claim 1, wherein the polymerizable monomer (Ax) is a compoundrepresented by the following formula (III);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X¹ is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y¹ represents a substituent having a molecular weight of 15 ormore; n1 represents an integer of 0 to 3; and, when n1 is 0, X¹ is ahydrocarbon group having two or more carbon atoms.
 5. The curablecomposition for imprints according to claim 1, wherein the polymerizablemonomer (Ax) is a compound represented by the following formula (IV);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X² is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y² represents a substituent having a molecular weight of 15 ormore, the substituent being other than an aromatic group-containinggroup; n2 represents an integer of 0 to 3; and, when n2 is 0, X² is ahydrocarbon group having two or three carbon atoms.
 6. The curablecomposition for imprints according to claim 5, wherein, in the formula(IV), R¹ is a hydrogen atom, or a methyl group; X² is a single bond, ora hydrocarbon group having 1 to 3 carbon atoms; n² is an integer of 0 to2; and, when n2 is 2, X² is a hydrocarbon group having one carbon atom.7. The curable composition for imprints according to claim 5, whereinthe compound represented by the formula (IV) has a molecular weight of175 to
 250. 8. The curable composition for imprints according to claim5, wherein the compound represented by the formula (IV) has a viscosityof 6 mPa·s or less at 25° C.
 9. The curable composition for imprintsaccording to claim 1, wherein the polymerizable monomer (Ax) is acompound represented by the following formula (V);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X³ is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y³ represents a substituent having an aromatic group and having amolecular weight of 15 or more; and n3 represents an integer of 1 to 3.10. The curable composition for imprints according to claim 9, whereinR¹ is a hydrogen atom, or an alkyl group, and X³ is a single bond, or analkylene group.
 11. The curable composition for imprints according toclaim 1, wherein the polymerizable monomer (Ax) is a compoundrepresented by the following formula (VI);

wherein X⁶ is a (n6+1)-valent linking group; R¹ each are a hydrogenatom, an alkyl group, or a halogen atom; R² and R³ each are asubstituent; n4 and n5 each are an integer of 0 to 4; n6 is 1 or 2; andX⁴ and X⁵ each are a hydrocarbon group which may have a linking groupcontaining a hetero atom in the chain of the linking group.
 12. Thecurable composition for imprints according to claim 11, wherein X⁴ andX⁵ in the formula (VI) each are an alkylene group, the alkylene groupbeing free from a linking group.
 13. The curable composition forimprints according to claim 1, which further comprises a polymerizablemonomer different from the polymerizable monomer (Ax).
 14. The curablecomposition for imprints according to claim 13, wherein thepolymerizable monomer different from the polymerizable monomer (Ax) is amonofunctional (meth)acrylate having an aromatic structure and/or analicyclic hydrocarbon structure.
 15. The curable composition forimprints according to claim 1, which further comprises a polymerizablecompound having a fluorine atom and/or a silicon atom.
 16. The curablecomposition for imprints according to claim 1, which further comprisesan antioxidant and/or a surfactant.
 17. The curable composition forimprints according to claim 1, which comprises 30% by mass or less ofpolymerizable monomers having a molecular weight of 2000 or more,relative to the total amount of all the polymerizable monomers containedin the composition.
 18. A cured product of the curable composition forimprints according to claim
 1. 19. A method for manufacturing a curedproduct comprising; applying the curable composition for imprintsaccording to claim 1, onto a substrate to form a patterning layerthereon, pressing a mold against the surface of the patterning layer,and irradiating the patterning layer with light.
 20. A reaction diluentcomprising a compound represented by the following formula (IV);

wherein R¹ represents a hydrogen atom, an alkyl group, or a halogenatom; X² is a single bond, or a hydrocarbon group which may have alinking group containing a hetero atom in the chain of the linkinggroup; Y² represents a substituent having a molecular weight of 15 ormore, the substituent being other than an aromatic group-containinggroup; n2 represents an integer of 0 to 3; and, when n2 is 0, X² is ahydrocarbon group having two or three carbon atoms.